TAC Tech => Mechanical => Topic started by: Maryland Bandit on March 05, 2007, 10:01:59 AM

Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Maryland Bandit on March 05, 2007, 10:01:59 AM
Thought a sub thread would be good for motor specific questions. We'll see how it works out. Sticky for now. Have fun with it guys.
TOM
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: 79T/Aman on March 06, 2007, 02:34:01 PM
I'll start the first post, this is a question I have seen sssoooo... many times, Pontiac big block VS small block, well there are no differences, the basic modern Pontiac V8 came to market in 1955 and remain the virtually the same until 1967 when it was more standerdized but the block has not changed in dimention and neether did the heads or intake.
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Ben on March 06, 2007, 05:51:24 PM
Quote from: "79T/Aman"
remain the virtually the same until 1967 when it was more standerdized but the block has not changed in dimention and neether did the heads or intake.

Technically this is true externally, but there are quite a few differences throughout the years.  In 1972 they changed the exhaust crossover port on the heads and intake, so earlier intakes on later heads will cause exhaust leaks.  Using gaskets and filler material can correct this problem.

The heads also have differences in them throughout the years, but externally they were mostly all the same and will bolt up from 1965-1979 (bolt pattern of intakes was different in 1964).
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Rick on March 06, 2007, 06:36:40 PM
Be aware that pre-68 heads were significantly different for 2 barrel engines and 4 barrel engines.  Yeah, they both bolt up to the block, but intake manifolds won't interchange on the heads.  I found that out about a year ago when somebody was going to use low compression heads from a 67 (or thereabouts) vintage engine with a 4 barrel intake.  It didn't match up at all. :oops:
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: 78thumper on March 06, 2007, 07:59:59 PM
After reading some of the sagas of engine builds gone bad, how about these.

The only similarity between a Pontiac V8 and a Chevy V8 is they both have 8 cylinders, period. :roll:

Find a machinist/engine builder who either knows Pontiac engines or is willing to learn. They do exist.  8)

If you really want to use a Chevy builder :?, build a Chevy engine or invest in a Pontiac shop manual and give it to him for reference.

As a matter of fact, insist that he uses it and check his work before accepting delivery.

After all, it's your money, you're the customer, and at one point in time (a long, long time ago), the customer was always right.  :shock:  :D
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Rick on March 06, 2007, 09:43:14 PM
I'm no machinist, so I've had my machining work done by the local NAPA guy who knows BOP engines.  I've ALWAYS done my own assembly work.  I just read the manuals (factory sevice and Chilton's plus whichever other ones applied) and then DID it.  I've never had an assembly problem.  Is it that hard?  I'm not particularly a wizard... :?  :?
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Ben on March 06, 2007, 10:39:20 PM
Quote from: "Rick"
It didn't match up at all.

Ports didn't match up or the intake didn't physically fit?  If it didn't physically fit, it's possible there was milling done somewhere on one piece that didn't match the others as a set.  I am not aware of any big differences between 1965-1968 intakes and later ones.  This is why you can run a tri-power on a 455 block.  If it was a 1964 or earlier, those don't fit.
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Rick on March 06, 2007, 10:46:43 PM
From what was reported to me, the intake manifold would bolt up but the intake ports didn't match.  What I don't know is what vintage the intake was.  The poster had asked if they would "fit" and from the info I had they would.  Then a few days later he told me they didn't.  No pictures to demonstrate the mismatch, but I felt bad that he'd popped for them and they wouldn't work for him.  I suppose it's possible they could have been earlier than he thought, though. :?
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Ben on March 06, 2007, 10:52:57 PM
Quote from: "Rick"
I suppose it's possible they could have been earlier than he thought, though.

Date codes are your friend!  My friend has a TON of stuff out at his place, the first thing we do is go for the date code.  That proves beyond a shadow of a doubt what it is.  No more "well maybe it fits?" questions.

Are we sure it was a Pontiac intake...?  Believe it or not that has been a problem...

1965-1979 intakes all interchange with each other, except for the exhaust port mismatch that needs to be addressed.  Linkage (http://www.slyagent.com/tech/p-intgs.htm). ;-)
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: yellowbird on March 07, 2007, 01:51:33 PM
Quote from: "78thumper"
After reading some of the sagas of engine builds gone bad, how about these.

The only similarity between a Pontiac V8 and a Chevy V8 is they both have 8 cylinders, period. :roll:

Find a machinist/engine builder who either knows Pontiac engines or is willing to learn. They do exist.  8)

If you really want to use a Chevy builder :?, build a Chevy engine or invest in a Pontiac shop manual and give it to him for reference.

As a matter of fact, insist that he uses it and check his work before accepting delivery.

After all, it's your money, you're the customer, and at one point in time (a long, long time ago), the customer was always right.  :shock:  :D


I agree, find an engine builder who know Pontiac. The fellow who built my motor was born in Pontiac Michigan, worked for Pontiac as a machinist and has been a machinist for 45 years. He did a fantastic job. I have seen too many Pontiac Olds motors built by Chevy guys and they were never right.
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Rivhard on March 07, 2007, 06:37:59 PM
I had "Pontiac Greg" Merrick out of Colorado build my engine.  He has been building Pontiacs for 20+ years.  He stressed NEVER have a Chevy guy work on my engine!! :D
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: sweet73 on March 08, 2007, 09:47:34 PM
One of my best friends is a chevy guy and he's always hinting to build me a pontiac motor but i've read too many horor stories on here about this subject so i'm not letting him touch my pontiac! I only want to install it once! I don't know enough about engines to oversee his work so i think paying a little for peice of mind is ok.
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: 78thumper on March 09, 2007, 08:58:41 AM
Quote from: "sweet73"
One of my best friends is a chevy guy and he's always hinting to build me a pontiac motor but i've read too many horor stories on here about this subject so i'm not letting him touch my pontiac! I only want to install it once! I don't know enough about engines to oversee his work so i think paying a little for peice of mind is ok.


Here's your chance to show him the light.

First off - Learn about your engine

Buy Jim Hand's book - How to Build Max-Performance Pontiac V-8s.

Get a Pontiac Service Manual - Hitman offers them on CD at his website www.78ta.com

Read both of them

Read anything else you can get your hands on about building Pontiac motors - HO Racing stuff, Herb Adams, search the internet, even Chiltons

Then try it. Use your manuals as your guide. When someone starts talking about how they would do this or that with a Chevy motor, just let them ramble on and tune them out :wink:

Believe it or not, most of us were not born knowing how to tear down and rebuild a Pontiac motor. :lol:

We had to learn by doing and reading.
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: 72Formula on March 13, 2007, 08:05:25 PM
Just gotta chime in here about machinists and Pontiac engines.  There's nothing magic about a Pontiac V8.  It's an internal combustion engine, the processes required to remachine it are the same as for any engine.  I would say that it doesn't require a machinist who is intimately familiar with Pontiac engines, it requires a machinist who is conscientious and careful and cares about the work he puts out.  It's okay if he does a lot of Chevy engines as long as he realizes that he needs to be checking specs and paying attention during the machining and especially the assembly process.

I worked for about a year at a high performance machine shop.  The guy had all the best machines and tools and he was a real perfectionist.  Most of the engines he built were Chevies because that's what most people are running, but before he built any engine he hadn't done before or in a long time he checked all the required specs and manuals.  During the time I worked there we built an LT1 for a roadrace '96 Camaro, a basic 350 and a 327 also (not sure what they were going into), a 454 for a custom '79 Camaro, a Chrysler 340 with all kinds of custom mods to the oiling system, an Olds 455, a Honda 1.6L for a turbocharged Civic, my 428, a friend's 455, and a 400 for a guy in my car club.  No problems with any of these engines because we took the time to make sure the work was done right and didn't ASSUME anything.

The big difference between a Pontiac V8 and a Chevy as far as assembly goes is the orientation of the connecting rods and pistons.  When it comes to machining, if your machinist isn't measuring the pistons first then finish honing the bores to achieve the correct clearance he isn't doing it right.  If he isn't checking to make sure the main bores are straight and within spec before proceeding, he's not being careful enough.  We routinely installed the bearings in the mains and rods then measured the actual diameters before sending the cranks out to be ground so we could tell the crank grinder exactly what diameter to grind the journals.  Then we double checked the clearances when we got the crank back to make sure it was done right.  We checked piston to deck height on everything, we checked crank endplay and rod side clearances against published specs, in anything other than the basic rebuilds we file fit the rings to each bore.  When we did a set of heads every seat got cut to the same depth and every valve got the same amount ground off it.  The valve guides were all finished to the same sizes.  The equipment he had was so accurate that every seat mated perfectly with every valve.  He had a guarantee that if you could bring in a set of heads that he couldn't improve the valve seal on he'd pay you $100 cash.  He never paid anyone.  This is the kind of attention to detail that allows a machinist to build any engine.  Of course you paid for that extra level of detail, but the people that brought their engines to that shop didn't mind because they knew the extra cost was worth it.

Too bad the owner had a drug problem and lost the business, I had a lot of fun working there.
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: 78thumper on March 14, 2007, 08:35:02 PM
Well 72 Formula

Sounds like you worked for the kind of engine builder I referred to in my second line in my initial post - find a machinist who knows Pontiacs or is willing to learn.

My intent was not to bad mouth Chevy builders, just to make sure folks realize that there are differences between Chevys and Pontiacs. Pontiacs are definately not assembled like a Chevy. You even stated that.

People need to make sure that their machinist will build them a reliable motor from the get go. There have been to many horror stories of motors being incorrectly assembled.
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: critter on March 24, 2007, 07:59:09 PM
Three rules for engine building.

1 - Cleanliness is next to Godliness.

2 - Measure everything twice with properly calibrated tools.

3 - If it seems wrong, it probably is and you should make sure.
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Kyledyr on April 11, 2007, 06:25:27 PM
we've got a poncho 400 at school out of a 4 speed 77 or 78 trans am.  the casting code is XA.  it has the chrome valve covers that came on a W72, but i think XA is for the regular 400. which is it?
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: John Wallace on April 12, 2007, 10:18:33 AM
Hopefully a 1977 XA.  :D

1978 XA is a 301.

But, then again the XA in 77 (and most other years) was for an automatic.

Try my engine search page:
Engine Search (http://www.wallaceracing.com/enginesearch4.htm)
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Kyledyr on April 12, 2007, 04:35:25 PM
hey i just linked someone to your page yesterday!  pretty nifty setup you've got there. ill ask my teacher about the year.
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Bandit 77 on May 03, 2007, 08:57:57 PM
just chiming in my 2 cents but to let every one know pontiac made there last engine in 1978 saving 10,000 for the 10th aversy cars.

i know lots of misc fact about 70-81 T/As
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Kyledyr on May 03, 2007, 09:14:45 PM
do you mean their last 400s?  because there was the 301's as well, which were still pontiacs.
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: HigPup on May 13, 2007, 05:52:46 PM
I have a 73 455, that starts no problems just turn the key, it runs rough, but haven't got carb dialed in yet.  It will idle  until it gets warm about 5-8 minutes, then starts to run rough and shuts off. The problem is after it gets warm it won't start unless I keep the gas pedal to the floor then pump the gas to keep it running, but then it will quit.    Also my water temp is at around 220 is that high or ok?  Any suggestions would be very helpful.

I have an MSD unilite distributor, Edlebrock Carb  750 cfm.
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: 79solargoldta on August 02, 2007, 12:21:52 AM
I'm trying to drop my 77' block pontiac 400 into my 79' TA that was originally an olds 403 and I'm having a BIG problem. The motor will not line up with the mounts that are on the frame, has anyone else run into this problem and what is a good solution? I've replaced the frame mounts with new ones from year one and I pulled the 400 mounts off of a wrecked TA with a 400 so everything should work....but isn't. This is VERY frustrating and any advise would help, thank you.
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: MR OLDS on August 30, 2007, 10:20:52 PM
It seems like we are getting into Pontiac engines now. Just finished a pump gas 464 with Edelbrock performer heads ported by us torqerII intake and Hyd roller cam. 578 HP and 607 TQ with a very flat power curve. Power peak was at 5500.
 Terry @ FCR Performance
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: BanditDave on August 30, 2007, 10:44:09 PM
Quote from: "79solargoldta"
I'm trying to drop my 77' block pontiac 400 into my 79' TA that was originally an olds 403 and I'm having a BIG problem. The motor will not line up with the mounts that are on the frame, has anyone else run into this problem and what is a good solution? I've replaced the frame mounts with new ones from year one and I pulled the 400 mounts off of a wrecked TA with a 400 so everything should work....but isn't. This is VERY frustrating and any advise would help, thank you.


Hey There,

Which engine mount brackets did you use? I believe you can leave the frame pads in the same spot as the 403s if you get the proper adapter bracket that Ame's and Perf Year's type places sell regularly in their catalogs. I can take a look at my 400 car outside this weekend for you as I used to have a 403 power TA as well so I am pretty sure we can sort this all out for you.

BTW, the gentleman who posted above me, Terry from FCR, is also a wealth of knowledge. Never hurts to give him a call.

Dave
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: 79solargoldta on August 31, 2007, 10:22:58 PM
Well I solved the problem. I lined up everything with the frame mounts attached to the block mounts, lowered the engine down onto the frame and aligned the trans mount up, made sure the engine was level and I marked where the holes were on the frame with nail polish. I raised the block up, took off the frame mounts, made sure the markings matched up and then drilled new holes in the frame! Every thing worked out great from there on out, I'll post pics in the next few days on the progress under the restorations section under "my 79 trans am restoration".
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: skirkpat on September 13, 2007, 04:55:56 PM
Question? I am new to T/A's , I have had more cars than most peoples families will have in a lifetime (numbering in the hundreds), but have somehow avoided building a BOP engine,
1)Which are better, 455 Olds/455 Pontiac?
2)which are easier to find/ build for performance?
3)I have a 403 Olds in there, is this worth building?
4) will my shaker line up with an Olds 455 (are the blocks the same?)
5)Sorry for this, but should I stick my 525 HP 402 BB Chevy with edelbrock heads that I have spent $5,000.00 on and is looking lonely on the floor?
I have a nice project that runs already, but is kinda weak, just thinking about a little speed down the road.
Thanks for reading
Sean
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: Rick on September 13, 2007, 08:19:24 PM
Well...my $0.02...

1.  Your choice -- Pontiac guys swear by Pontiacs, Olds guys by Olds...but I think the Pontiac 455 is a little easier to fit in the F-body bay.  The Olds 455 will fit in there (several guys here have done it) but it appears to be a little more work.

2.  Your choice, again, along with whatever you can find in the wrecking yards at this late date.

3.  It depends on what you want the engine to do?  Cruise reliably on the street for forever?  The 403 will do that, and put out quite a bit of power with the right tweaks.  Just don't figure on twisting its tail into the higher RPMS -- the block really wasn't meant for that.  But there's nothing wrong with the 403 for street use.

4.  No.  You'll probably have to fab your own or go for a WFO setup.  The proper location of the shaker is pretty sensitive to all sorts of things -- engine height, manifold used, carb used -- and if you get very far at all from the Pontiac V8 dimensions all of the sudden it doesn't work right, if at all.

5.  Again, depends on what you want from your car and how much work you want to put into it.  BB Chevys WILL fit into the F-body, but again it's a not insignificant amount of work.  But if you've spent $5,000 on that engine, maybe it's not so much work that you won't want to do it.

Just my $0.02...somebody else will be along shortly to take potshots at us both, I'm sure... :P  :P  :wink:
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: 79solargoldta on November 19, 2007, 04:04:59 PM
I need help, I had my motor running and now when I go to start the engine it just keeps turning and it sounds like it is about to start and I give it some gas then it just putters out. I smell gas comming from the engine, is it too rich? I did adjust the throttle screws, but it was because I was having the same problem. Any suggestions would help. BTW it's a 400
Title: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on November 20, 2007, 05:23:21 AM
Sounds like its flooded....don't pump the accelerator, just hold the throttle fully open while you crank...this lets the most air get into the engine to clear the fuel flooding.
If it doesn't start after some cranking with the throttle fully open, then its time to check ignition timing and operation etc.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: SteeleBird on December 21, 2007, 10:39:59 AM
hello, I'm new to the site, and new to pontiacs. I have a 74' 400 I have just had milled, and installed a rebuild kit. I got the pistons,rods,crank,and heads on it. I'm stuck on the timing chain cover/waterpump cover. Its been nearly a year since I tore it down, and now I cant remember how it all goes back together. Are there any old threads, or a place i can look on-line that would have a diagram or manual to go by to get this thing back together. I have a Haynes shop manual, but it does not go into enough detail for me. I need an exploded view or something to look at for refrence.  thanks in advance for any and all help.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Rick on December 21, 2007, 02:53:35 PM
Welcome to TAC!  We're all about projects here, and we love pictures, so post some up of what you've got. :lol: :lol:

With regard to your specific question, there's nothing that beats the factory service manual for things unique to the engine.  Haynes and Chilton's are great for general stuff, but to get the best pics and diagrams you need the Pontiac service manual.  Hitman sells them over on his site in CDROM form, and personally I think the CD version works better than the old printed versions (I have both).  You can check them out at:

http://www.78ta.com/sale/cdsale.htm
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 79solargoldta on December 24, 2007, 11:24:52 AM
Hey guys, I need some carburetor help on my 400. It's a 77' block with a Q-jet off of my old 403. My question is: My secondary's aren't opening up with acceleration and even on WOT. I was wondering if you guys had any ideas to why this might be happening? All vaccum lines are hooked up, but I did rebuild the carb myself and it's the first one for me. Also I'm getting this thin carbon film mixed with water or spent fuel out of my exhaust pypes that ends up in a puddle when I'm fooling around with the carb in the garage, any idea of what this is? Thanx for the help!
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on December 25, 2007, 05:51:42 AM
hello, I'm new to the site, and new to pontiacs. I have a 74' 400 I have just had milled, and installed a rebuild kit. I got the pistons,rods,crank,and heads on it. I'm stuck on the timing chain cover/waterpump cover. Its been nearly a year since I tore it down, and now I cant remember how it all goes back together. Are there any old threads, or a place i can look on-line that would have a diagram or manual to go by to get this thing back together. I have a Haynes shop manual, but it does not go into enough detail for me. I need an exploded view or something to look at for refrence.  thanks in advance for any and all help.

Just did this the other day.....pretty straight forward. Don't tighten the four large bolts in the front till you start the small ones in the front of the sump. Don't forget to install the two spacer rings that fit into the block on the two lower front bolt holes..they locate the timing cover correctly. Install a new soft rubber ring seal where the cover meets the manifold...I also used a slight wipe of sealant on it for luck. I used loctite sealant (the type that always remains flexible) on all the gaskets.
I used new transfer tubes (you can get stainless ones now), use a bit of anti sieze on them where they go through the alloy case. I also used a new stainless divider plate and clearanced it down close to the water pump fins...to make the pump more efficient.
Theres two large bolts that go through the water pump and the timing cover int othe block...coat them with anti sieze before fitting or they'll corrode to the cover. install two smaller bolts at the upper LH side before installing hte bolts with the alternator bracket (one big and one small).
Don't forget to install the long bolt and special washer that ties the timing cover to the manifold and seals the rubber ring at the back of the cover.
Any other ?, ask away.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on December 25, 2007, 05:55:52 AM
Hey guys, I need some carburetor help on my 400. It's a 77' block with a Q-jet off of my old 403. My question is: My secondary's aren't opening up with acceleration and even on WOT. I was wondering if you guys had any ideas to why this might be happening? All vaccum lines are hooked up, but I did rebuild the carb myself and it's the first one for me. Also I'm getting this thin carbon film mixed with water or spent fuel out of my exhaust pypes that ends up in a puddle when I'm fooling around with the carb in the garage, any idea of what this is? Thanx for the help!

I'm not really the best to ask on fooling around with a Qjet....but the watery grey stuff thats blows out your exhaust is just condensation....mine does the same when its warming up, sprays drops of carbon and water on the floor of the garage.....goes away when the exhaust warms up.
This is what causes exhausts of cars to rust out...especially those used for short runs where the exhaust never really heats up properly and evapourates the condensation.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 79solargoldta on January 08, 2008, 02:03:49 AM
How hard is it to change out the water pump? Do I have to drain all the coolant and oil?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: tomriffs on January 08, 2008, 05:34:10 PM
i have a numbers maching 69z.i race a74 vega smsll block ,i had a68 gto, in high school a 70 427 camaro right out of high school i consider myself a chevy guy i bought a 78 y88 nunbers matching last year done a resto stickers and all and found differences in the motor basicly the same but there is a lot of different things do your homework mine runs and sounds great and the torque wow! its a stock w72 to the bone i love it
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: blackturbo on February 28, 2008, 08:33:29 PM
hope this is the right forum to post this, but me and a buddy were in an argument tonight that my 78 ta with the pontiac 400 came with a cat converter or not... he says I have one,, and actually the car is sitting under a cover outside in a mudpit with all the rain weve had... so I ask the question... did the 78 ta have cats from the factory? I told him no because I noticed it doesnt have any other emissions on it like a smog pump..

mark
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Rick on February 28, 2008, 09:23:55 PM
hope this is the right forum to post this, but me and a buddy were in an argument tonight that my 78 ta with the pontiac 400 came with a cat converter or not... he says I have one,, and actually the car is sitting under a cover outside in a mudpit with all the rain weve had... so I ask the question... did the 78 ta have cats from the factory? I told him no because I noticed it doesnt have any other emissions on it like a smog pump..

Every GM car made in 1978 for domestic use was required to be EPA certified for emissions compliance.  They ALL had single exhausts with a single catalytic converter.  Other smog equipment (such as AIR pumps) was added to bring it into compliance with specific area requirements, like high-altitude and California smog limits.  But the catalytic converters and EGR valves and stuff like the EFE valves were used across the board.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: rkellerjr on February 28, 2008, 09:30:36 PM
Welcome to TAC Steelebird, did you get the front end of that motor back on?  Here's a thread that might help...

http://transamcountry.com/community/index.php?topic=2381.0

This is a rebuild of my '77 400 but the engines should be pretty much the same.  There should be pics that can help you with the front end of that motor.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: TA Addict on March 03, 2008, 02:54:42 PM
79solargoldTA said:
Quote
Hey guys, I need some carburetor help on my 400. It's a 77' block with a Q-jet off of my old 403. My question is: My secondary's aren't opening up with acceleration and even on WOT. I was wondering if you guys had any ideas to why this might be happening?

  Can you open the primaries all the way and verify that the secondary throttle valves are opening all the way too?   You'll have to hold the secondary top butterfly valves open by hand and look down inside the carb to be able to see the actual secondary throttle valves.   Once the secondary throttle valves do open there is nothing mechanical involved in opening the secondary butterfly valves.   They operate purely be airflow.

  Did you make any adjustment to the tensioning screw that controls the force required to open the secondary butterfly's?   Probably not as they aren't something that jumps out at you unless you're really looking for them.

  Guess I should really ask 1st how you know the secondaries aren't opening.   Is it just that you never feel a sudden surge of power?   Some cars are adjusted well enough that you don't feel a sudden kick when the secondaries open.   

  Check the two above suggestions and if see if that helps - if not come back and I'll do what I can to help.

  TA Addict
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: brian c on March 06, 2008, 08:20:01 AM
Need some engine building suggestions for a 400 I'm going to be building for my sister. She wants a good smooth idle and no where near the 400hp my built 469 is pushing.

I was thinking of an Edelbrock Performer intake/cam/lifter setup but I'd like it to be a tad warmer than the stock 200/220hp these pushed out. I'm thinking somewhere in the neighborhood of 250-275hp at the crank. Any thoughts on a good cam to run with the Performer intake?

Head wise I'll probably snag a set of 6x-8's off ebay and have them gone through. Gear wise I'm thinking of 3.08:1's so she gets decent gas mileage and I'll add in a posi while I'm at it. Tranny wise I'm looking at a TH350.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: BoDarvelle on March 09, 2008, 01:27:42 PM
I just finished the swap from a 400 to a 455 in my T/A. 

I could help if anyone has any questions :cool:
(http://i161.photobucket.com/albums/t234/bodarvel/100_0456.jpg)
(http://i161.photobucket.com/albums/t234/bodarvel/100_0457.jpg)
(http://i161.photobucket.com/albums/t234/bodarvel/August2007034.jpg)
(http://i161.photobucket.com/albums/t234/bodarvel/August2007033.jpg)
(http://i161.photobucket.com/albums/t234/bodarvel/August2007019-1.jpg)
(http://i161.photobucket.com/albums/t234/bodarvel/August2007018-1.jpg)
(http://i161.photobucket.com/albums/t234/bodarvel/CarPicsMarch2007008.jpg)
(http://i161.photobucket.com/albums/t234/bodarvel/CarPicsMarch2007007.jpg)
(http://i161.photobucket.com/albums/t234/bodarvel/CarPicsMarch2007006.jpg)
(http://i161.photobucket.com/albums/t234/bodarvel/10-14-200648.jpg)
(http://i161.photobucket.com/albums/t234/bodarvel/100_0455.jpg)
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: chief poncho on March 21, 2008, 04:24:32 PM
WOW! Very nice and what looks to be a very potent poncho powerplant in that bird.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: TnVTX on March 21, 2008, 04:35:28 PM
Bo,
Where did you get that shaker lower pan/air cleaner assembly?
I have a WFO, and my shaker still sits too high.
I'm also thinking about switching to a "Dude" scoop also.
(http://216.77.188.54/coDataImages/p/Groups/267/267538/pages/862983/2nd468.JPG)
(http://216.77.188.54/coDataImages/p/Groups/267/267538/pages/862983/3rd468.JPG)
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Doug on April 15, 2008, 07:34:14 PM
Bo,
Where did you get that shaker lower pan/air cleaner assembly?
I have a WFO, and my shaker still sits too high.

I did have that same problem but Larry Navarro figured it out from the pics.  The shaker had been moved about an inch forward on the base.  Once I put it back it worked perfectly.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Donkey on April 22, 2008, 01:45:12 PM
Im pretty sure the 350 driveshaft will work...not 100% sure though...
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: grenggli on April 22, 2008, 08:29:09 PM
Concerning 455 with th400 COMBO in 1980.  I did this in a 1981 and you do have to have a shorter driveline because the TH400 is longer by @1 inch.  You can have a driveline shop cut down your TH350 one but you will need to attach a TH400 yoke because they have a larger output shaft.  I got lucky and purchased a shorter one out of a car with your set up for mine and it fit perfectly.  If you try to use the TH 350 driveline without shortening it, you are likely going to have issues since the slip yoke is not going to be inside the transmission at a spot where the rearend going up and down can have room to move and slip with it.  Good luck on your modifications.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Tony79WS6 on April 29, 2008, 02:34:20 PM
Hey, I have a few questions for you guys. I am building up a Pontiac 400 right now, and I have a question about windage trays and crank scrapers. First off, the motor is a 1974 block, and when I took it apart, there was no windage tray in there. It's being built for street/strip duty with a stock-style oil pan. Do I need to get a windage tray, a crank scraper, both, or neither? I don't want to have oil starvation issues on my new motor.

Also, I'm running 1971 #96 D-port heads and was wondering if I have to drill extra bolt holes to mount a set of headers. I am probably going with some Hedman 28156's, and on Summit's website, it says that some heads need to be drilled for extra mounting holes.

Thanks!!! 8-)
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Rick on April 29, 2008, 07:06:48 PM
Pontiac stopped using windage trays in the early 70s.  They were not in the 74-76 engines I've had.  If you're concerned about oil starvation you should look into an accusump.  That provides about a quart of oil reserve at system pressure in case the pickup gets uncovered.  Mine has worked pretty well. ;)
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Tony79WS6 on May 06, 2008, 11:03:06 AM
I have some more questions about my 400 build for you guys.  :smile:

1. On the subject of the windage tray again, do I really need one? I spoke with my engine builder today, and he said that it was definitely a good idea to get a stock-style one, but I'm also going to have to get different main cap bolts for my 1974 block, because it was not originally equipped with one. I am having trouble finding both the tray and the bolts together. Does it really matter that much?

2. I need to know what I need inside of the timing cover when it comes to cooling stuff. Right now, I just have the cover, and I know I need a water pump divider plate, but what else do I need? 

3. I plan on running an Edelbrock Performer RPM manifold on my 1971 #96 heads, and I want to know if I need to block off the heat crossovers on the heads. Does that manifold already do that, or is there something else I need to buy?

4. And one more quick thing: I need a heater hose nipple for my cylinder head, because mine is not useable anymore. Ames Performance has them backordered, and I want to know if there is somewhere else I could get them.

Thanks!!!
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: brian c on May 06, 2008, 11:43:27 AM
1. You can buy an aftermarket tray and bolts - I want to say Milidon (sp?) but I don't have a catalog handy. When I bought my stock windage tray it did not come with the mounting bolts and I believe the machine shop just supplied those when they assembled the engine for me.

2. If you have the divider plate you're almost there. There's (2) inserts that you may/may not have already in the timing chain cover. If you don't have them you need to get them. They look like this:

(http://www.frankspontiacparts.com/usedparts/2742c4870.jpg)

3. I didn't have anything filled in my heads and its run for 500 miles so far. Nothing was mentioned by either the machine shop or by Muscle Car Alley when I had them fix the intake gasket issue the machine shop created.

4. I've heard that you can get them right from your GM dealer. Otherwise I'd wager you can find them at any pontiac parts dealer - Franks Pontiac Parts lists them on their website for ~$30 (http://www.frankspontiacparts.com/usedparts/pontiacengineparts.htm) OR Spotts has them listed for $22 (http://www.spottsperformance.com/cooling%20system).
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Tony79WS6 on May 07, 2008, 01:07:34 PM
Are these (http://www.bopengineering.com/images/rubber_seals_b.jpg) the same as the steel ones? BOP Engineering sells these rubber ones, and I just wanted to make sure they work before I buy them. They are the only ones who have both the heater outlet for the head and the water pump plate in stock, so if I could get it all in one shot, that would be awesome.

Also, I was flipping through my How To Build Max Performance Pontiac V8s book last night, and it says that windage trays are pretty much unnecessary at the power level I'd be running, so I think I'll go without one.

I have another question about shaker height and intakes. If I use a Holley 4150-series with a stock or Edelbrock Performer intake with a 1 inch spacer/adapter, would that screw up shaker height? I would think that it would, but I'm just checking.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: mark369 on May 07, 2008, 01:19:56 PM
 On my 78 400 Pontiac head there is a port in the center on top to the intake manifold that is not covered by the gasket and with the intake on it is part visible and open to collect water cause my Mr gasket scoop does not allow a seal to the hood. Is there a purpose to this? 

(http://i245.photobucket.com/albums/gg46/mark3693/exhaust%20manifold/IM001132.jpg)
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 72blackbird on May 14, 2008, 12:32:21 AM
The center port is there to allow exhaust gas to enter a chamber under the stock manifold and warm the incoming A/F mix going into the intake ports (supposed to help atomize the fuel better). You will need to get intake gaskets that line up to these center ports if you are running the stock manifold, or a gasket that covers the hole completely if you using an aftermarket manifold. Fel-Pro covers just about every production Pontiac gasket you would need- ask your local speed shop or auto store to check their catalog for the right part no.

Geno
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: mark369 on May 14, 2008, 01:47:00 PM
That is the gasket that was on the car and the replacement one from Advance auto parts matches it!   Any idea what gasket # I should use & where to get it.  As is water gets in there and then boils out when I run the car.  Not good in winter. Its a wonder I have not had issues in the past. Ben that way for 10 years.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 72blackbird on May 14, 2008, 08:26:27 PM
That gasket is for a 68-71 head (my no.48s have the smaller exhaust port hole)- Fel-Pro makes the correct gasket for your application, where the top edge of the gasket runs straight across and seals that hole. BTW, what is the head no., 6X ? Are you running the stock manifold, or aftermarket? You may have to contact an expert Pontiac builder to get the right gasket.

Geno
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: CopMagnet on May 15, 2008, 08:01:34 AM
I'm looking for a poncho engine to replace a 403.  I'm torn between a 400 and a 455.  Are there any good links anyone can provide to inform me of the TRUE differences.  I've always heard vague info about the subject.  Like, They're the same engine, the 455 just has a larger bore....etc.  Forgive me, I know my way around a car, but I'm not an engine expert.  Thank for any info
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 72blackbird on May 15, 2008, 02:10:42 PM
CopMagnet,
The 400 has a 3.00 main journal dia., 4.120 bore x 3.75 stroke, and the 455 has a 3.25 journal dia., 4.15 bore x 4.21 stroke. The 455 has more torque, but the 400 is known for its ability to rev- both use the 6.625 rod.

I personally would get a Poncho 400, and then get either a 455 or 462 stroker kit. A stroked 455/462 Pontiac is better than a stock 455, because of the smaller main journal diameter (3.00 vs. 3.25) and its ability to rev faster (also related to main journal diam.). The 455 stroker kit uses a 6.625 (stock Pontiac length) rod and 4.21 stroke crank, while the 462 uses a BBC 6.8 rod and 4.25 stroke- the jury is out on which stroker is best, but in either case you can upgrade from a cast crank to a forged unit for $300 more. Both kits offer either 4340 I-beam or H-beam rods. The 462 also uses custom pistons, but those are usually lightwieght race units w/ floating pins. Butler Racing, Ohio Crankshaft, SD Performance, and Pacific Performance racing all offer stroker kits fof around $1400-2100.

Geno


Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: CopMagnet on May 15, 2008, 06:41:03 PM
That's some good info Geno, and hey, welcome to TAC bro!  Thanx   :cool:
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 72blackbird on May 16, 2008, 12:28:01 AM
CopMagnet,
No worries-glad I could share. BTW, when you're block shopping avoid any 400 blocks numbered #500557 and #568557- these are the thin-wall castings that came out in mid '75 to save weight. I have seen these at Pacific Performance racing in Ace's shop, and there is a big difference in wall thickness. I suppose they're okay for a stock  build-up, but not for a 550-hp 455 or 600-hp 462. Jim Hand's book aslo mentions the #481988 blocks, but I've got two and both of them are thick under the main caps (works for me).

Geno
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: CopMagnet on May 17, 2008, 12:33:13 AM
Geno, I am now officially required to buy you a beer.  I have an old knucklehead buddy from way back in high school, he swears 455 is better.  Well, I have thrown some info at him but, to no avail.  he went to mechanic school after leaving the army and I think he's pretty good.  However............some things just don't always add up.  He blew up 3 400's, well, maybe those were the ones with the thin wall castings that he didn't know about.  Can't wait to throw that at him to see what he says.  Hopefully, he'll man up and admit he didn't know about it.  I'm gonna look for a 400 just to piss him off.  I keep telling him to get on the net and join the 21st century, but he's one of those guys...    Geno, you rock, thanx  Chris Rocklin
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 72blackbird on May 18, 2008, 12:44:38 PM
Chris,
I've blown up a couple of 400's myself- the frist one threw a rod and grenaded that block, the second broke a crank but the block survived (!). You have to rev them for a bit for this to happen, but I'll tell you firsthand that stock Pontiac cast rods and cranks weren't meant for top end or road racing. Good thing there are plenty of sources for forged Pontiac rods and cranks now- we can build up a strong motor just the Chevy and Ford guys and show them how a Poncho makes power.

BTW, you don't need 4-bolt main caps- if you find a 2-bolt block, just run ARP  main studs- the general consensus is that they're good to 600-650 hp. And the cast cranks are strong enough if you keep the revs down and prep it properly (I personally would still get a forged crank 'cause it's only $350 more, and for the peace of mind). I'll buy the second round if you're ever in SoCal...

Cheers,
Geno
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Rob on May 18, 2008, 08:31:36 PM
can somebody help me ID my 455? comparing my code to 78ta.com's engine ID's, im guessing it's a 1970 455 HO? It's a Pontiac block for sure though right? My reading was engine code:YC casting code:C293897; Im also trying to ID my 400..sorry for it being blurry, my battery was dying out so I had to take it fast..ill take a clearer picture tomorrow..this is what i got for the 400; engine code:YH casting code:0151580 Im guessing its a 1974 400?.. Can anybody help me ID what I got? thnx in advance


455 Block
(http://i23.photobucket.com/albums/b365/94025/DSCN6087.jpg)
(http://i23.photobucket.com/albums/b365/94025/DSCN6086.jpg)

400 Block
(http://i23.photobucket.com/albums/b365/94025/DSCN6088.jpg)
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Rick on May 18, 2008, 08:50:24 PM
You have the entire list of possible combinations, don't you?  This site lists them all and has been pretty accurate from all reports.

http://www.teufert.net/identify/identify.htm
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Jdogg on May 21, 2008, 06:53:02 AM
i just bought a Turbo Trans Am that has a olds 455 in it, it dont work the guy that i bought from said he thinks it has a spun bearing maybe, is the motor worth saving? does it have any value to it? I think i am going to put a 355 int he car any special things i should know? It has a BW trans

thanks
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: BAN on June 05, 2008, 11:29:31 AM
Roller Cam in a 400?

Looking at rebuilding my top end, aluminum heads, carb and intake. Along with a r-cam. Is anyone running roller lifters in their 400 without a lifter guide plate? Is it something you can do as long as your cam is less than xxxx?

I'm asking as i dont want to have to tap threads into the valley to install the plate, and someone i was talking to on the weekend said something along the lines of "i'd never go a roller without a lifter guide in those engines" But im not too sure on this guys knowledge, seems to be one of those guys who talks alot.

Cheers
Sam.

Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Enzo_Guy on June 22, 2008, 08:08:51 PM
And the cast cranks are strong enough if you keep the revs down and prep it properly (I personally would still get a forged crank 'cause it's only $350 more, and for the peace of mind).

John Kaase actually used a cast steel crank in his first Pontiac Engine Masters entry and it held up just fine he said.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Enzo_Guy on June 22, 2008, 10:02:58 PM
can somebody help me ID my 455? comparing my code to 78ta.com's engine ID's, im guessing it's a 1970 455 HO? It's a Pontiac block for sure though right? My reading was engine code:YC casting code:C293897; Im also trying to ID my 400..sorry for it being blurry, my battery was dying out so I had to take it fast..ill take a clearer picture tomorrow..this is what i got for the 400; engine code:YH casting code:0151580 Im guessing its a 1974 400?.. Can anybody help me ID what I got? thnx in advance

This is a list of what a YC block could be:
YC A-body 76 400 170 Turbo 350 L-65 N 1x2 500557 2 AC
YC B-body 76 400 170 Turbo 350 L-65 N 1x2 500557 2 AC
YC B-body 76 400 170 Turbo 350 L-65 N 1x2 500557 2 AC
YC B-body 65 389 290 Turbo 400     1x2 9778789 2 AC
YC B-body 66 389 290 Turbo 400     1x2 9778789 2 AC
YC B-body 67 400 290 Turbo 400     1x2 9786133 2 AC
YC A-body 72 455 250 Turbo 400 L-75 Y 1x4 485428 2 GTO
YC A-body 71 455 325 Turbo 400 L-75   1x4 485428 2 GTO
YC A-body 70 455 360 Turbo 400 L-75   1x4 9799140 4 GTO Judge HO
YC B-body 69 400 290 Turbo 400     1x2 9790071 2 int seat 30
YC A-body 74 350 170 Turbo 350 L-30 N 1x2 488986 2 low comp
YC F-body 74 350 170 Turbo 350 L-30 N 1x2 488986 2 low comp
YC A-body 73 455 250 Turbo 400 L-75 Y 1x4 485428 2   
YC B-body 72 455 250 Turbo 400 L-75 Y 1x4 485428 2   
YC B-body 72 455 250 Turbo 400 L-75 Y 1x4 485428 2   
YC B-body 73 455 250 Turbo 400 L-75 Y 1x4 485428 2   
YC B-body 73 455 250 Turbo 400 L-75 Y 1x4 485428 2   
YC B-body 71 455 325 Turbo 400 L-75   1x4 485428 2   
YC B-body 71 455 325 Turbo 400 L-75   1x4 485428 2   
YC B-body 68 400 290 Turbo 400     1x2 9790071 2   
YC F-body 73 455 250 Turbo 400 L-75 Y 1x4 485428 2   
YC F-body 71 455 325 Turbo 400 L-75   1x4 485428 2   

Your casting code is not the number just above the block code, your casting code is actually on the block under the distributor cap.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: ole farmer on June 24, 2008, 10:01:30 AM
On my 78 400 Pontiac head there is a port in the center on top to the intake manifold that is not covered by the gasket and with the intake on it is part visible and open to collect water cause my Mr gasket scoop does not allow a seal to the hood. Is there a purpose to this? 

(http://i245.photobucket.com/albums/gg46/mark3693/exhaust%20manifold/IM001132.jpg)
I just noticed this on my 76 400 also. the Gasket covered (and sealed) the exhaust port but there is a small void above the exhaust port that is sort of no-mans land ??? The intake manifold has the smaller exhaust transfer port and all the intake ports line up but not the heat riser port. Did my engine get a manifold swap or is this just the way it is???? Thanks Guys...Garry
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: bandit79 on July 03, 2008, 08:14:01 AM
Roller Cam in a 400?

Looking at rebuilding my top end, aluminum heads, carb and intake. Along with a r-cam. Is anyone running roller lifters in their 400 without a lifter guide plate? Is it something you can do as long as your cam is less than xxxx?

I'm asking as i dont want to have to tap threads into the valley to install the plate, and someone i was talking to on the weekend said something along the lines of "i'd never go a roller without a lifter guide in those engines" But im not too sure on this guys knowledge, seems to be one of those guys who talks alot.

Cheers
Sam.




Sam,

While regular tappet lifter actually rotate in the lifter bore, roller lifters have to stay in one position. Therefore, you will need something that keeps them from rotating. A lot of the aftermarket roller lifters are tied together in pairs by a tie bar to keep them from rotating, they look like this  http://www.compperformancegroupstores.com/store/graphics/00000001/High_Energy_Hydraulic_Lifters_853_600x600.jpg (http://www.compperformancegroupstores.com/store/graphics/00000001/High_Energy_Hydraulic_Lifters_853_600x600.jpg), or they have retainers that slide over a pair and then the "spider" plate is bolted to the center of the valley that has "arms" that hold the retainers and it looks like this, http://www.compperformancegroupstores.com/store/graphics/00000001/Hydraulic_Roller_Lifter_Installation_Kit_08-1000_600x600.jpg (http://www.compperformancegroupstores.com/store/graphics/00000001/Hydraulic_Roller_Lifter_Installation_Kit_08-1000_600x600.jpg)

You will need either one or the other. But you have to run one of these setups. So yes you can run without the big plate in the valley, but you will have to run them with the tie bars. I hope this helps you figure it out.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: BAN on July 11, 2008, 12:15:00 AM
Thanks for the reply! Yeah im aware of the link bars used when retrofitting roller lifters to an engine (been around chevys quite sometime) This all started when some guy up here who supposedly "knows pontiacs" mentioned i wouldnt be able to get any lift due to the lack of length in the lifter bores themselfs. He basically explained to me that the lifters would "walk" around without a guide plate when they were at their highest lift. It confused me as ive never heard of this, even in custom race blocks where cams have been relocated.

Anyhow after digging into this 400 and reading a few things i realized he was totally full of B/S, and he owns a "performance store"  :shock:

So thanks for the reply, and while we are here. I thought i read something about replacing the stock valley pan due to clearance issues from the link bars in the roller cam, is this the case? or are you guys running stock pans with a roller setup?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Rebel 5150 on July 11, 2008, 10:53:12 AM
On my 78 400 Pontiac head there is a port in the center on top to the intake manifold that is not covered by the gasket and with the intake on it is part visible and open to collect water cause my Mr gasket scoop does not allow a seal to the hood. Is there a purpose to this? 

(http://i245.photobucket.com/albums/gg46/mark3693/exhaust%20manifold/IM001132.jpg)
I just noticed this on my 76 400 also. the Gasket covered (and sealed) the exhaust port but there is a small void above the exhaust port that is sort of no-mans land ??? The intake manifold has the smaller exhaust transfer port and all the intake ports line up but not the heat riser port. Did my engine get a manifold swap or is this just the way it is???? Thanks Guys...Garry

Are you talking about the 'port' that is cicrled in red in this picture?
(http://i222.photobucket.com/albums/dd16/hs78ta/1aponcho.jpg)

If so, the gasket is not supposed to cover that.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: mark369 on July 11, 2008, 11:16:44 AM
Yes the port circled in RED!  Ok, it is not supposed to be covered. But why? is it left open.  With a properly sealed shaker it does not get rain in it. With my Mr. Gasket scoop set up it fills with rain water and boils out when running. Worried about winter water freezing in it.   
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Rebel 5150 on July 11, 2008, 12:56:00 PM
Yes the port circled in RED!  Ok, it is not supposed to be covered. But why? is it left open.  With a properly sealed shaker it does not get rain in it. With my Mr. Gasket scoop set up it fills with rain water and boils out when running. Worried about winter water freezing in it.   

  Pontiac added it to keep the hot exhaust gases away from the oil soaked areas under the rocker cover and baking it in there.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Tony79WS6 on July 11, 2008, 02:22:47 PM
Here's a question that I hope someone can answer:

I'm putting my 400 on an engine stand tonight for assembly (I just got it all back from the machine shop!!!!!  :D) and I need to know what size the bolts are on the transmission side of the motor so I can mount it up on the stand. Please let me know if anyone knows! Thanks!  :cool:
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Rebel 5150 on July 11, 2008, 02:27:53 PM
3/8" coarse (16 threads per inch).
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Tony79WS6 on July 11, 2008, 02:43:04 PM
Thank you very much!!! I can't wait to get this beast in the car.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Tony79WS6 on July 22, 2008, 03:11:43 PM
Here's another question for you guys: What's the best way to put headers in the car with the engine already out? Should I atach the collectors to the rest of the exhaust and drop the motor on top of them, or should I attach the headers to the motor while it's still on the stand and drop it all in at once?

Thanks!
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Doug on July 25, 2008, 10:02:48 AM
Here's another question for you guys: What's the best way to put headers in the car with the engine already out? Should I atach the collectors to the rest of the exhaust and drop the motor on top of them, or should I attach the headers to the motor while it's still on the stand and drop it all in at once?

Thanks!

Generally you are better off setting the headers down then lowering the motor until it is a few inches above the mounts then attach the headers.  Of course if you are using shortys then attach them first and drop the whole thing in.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: cspella on September 24, 2008, 12:40:38 PM
so im new to the pontiac world i just bought a 76 trans am with the 400. the numbers i have gotten off the internet lead me to believe the engine is as strong as i may need what can be done to up the power
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Doug on September 24, 2008, 12:45:52 PM
so im new to the pontiac world i just bought a 76 trans am with the 400. the numbers i have gotten off the internet lead me to believe the engine is as strong as i may need what can be done to up the power

Exhaust, cam and heads would be the first order of business
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Mr. P-Body on September 27, 2008, 11:42:10 AM
cspella,

   Get Jim Hand's "How to Build Max-performance Pontiac V8s", published by SA Designs. This has been mentioned in earlier posts, but always needs to be "re-mentioned"...  It is the only CURRENT  study of the Pontiac V8.  It's intended for high performance street engines, and not intended for a true "race" engine.

   '76 400s were complete "smogger" engines. Dramatic power gains can be had by changing a few key pieces. If it's original, it's time for a rebuild and those changes can be made more easily during that rebuild. It's no problem at all to get 350-400 HP on 93 octane fuel and still use the stock converter and rear gear.

  If you need more specifics, just say so!

Jim
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Bandit 77 on September 30, 2008, 12:19:16 PM
any ever replaced the dip stick tube and guide that attaches to the #3 main cap.  mine is missing so any pick on what it looks like and excally how it bolts on would be greatly appricated.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Tony79WS6 on September 30, 2008, 12:32:27 PM
any ever replaced the dip stick tube and guide that attaches to the #3 main cap.  mine is missing so any pick on what it looks like and excally how it bolts on would be greatly appricated.

I just went through this on my 400 recently. First off, and not to scare you, but you're probably going to have to yank the motor to do this. If you've already done this, then you'll need this:
(http://www.bopengineering.com/images/inner_dipstick_tube_s.jpg)
It's the one with the tab coming off of it. You'll also need this:
(http://www.bopengineering.com/images/pontiac_dipstick_tube_s.jpg)
This one gets pressed into the dipstick hole. I slightly pressed in the outer one first and then installed the bottom part that attaches to the main cap. It bolts on with 2 bolts attached to the cap. Then, I pressed the top in until it met the bottom tube.   

Where did the old ones go?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Bandit 77 on September 30, 2008, 06:49:14 PM
dunno, they werent there when i repaced the main bearings and having never been in the bottom of a pontiac motor didnt know they were spose to be. long story short i noice a cut off dip stick and figure i would replace it when i was done, first time i fired up the motor it shot the new dip stick right out from under the hood.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: OriginalHO on October 01, 2008, 04:58:47 PM
BTW, there was an early question in this thread about bolt size at the back of the block to attach an engine stand or bell housing.  At least 1963 (which I recently assembled) had 7/16 NC, not 3/8 NC.  Does anyone know what year Pontiac changed that? 

It surprised the heck out of me, although I did some work on real early blocks, but that was too long ago and I didn't remember that difference.  Fortunately, I had  a set of 7/16 NC grade-8s for my engine stand that I had used on my Packard V-8s.

Regardless of size, be sure to use grade-8, not grade-5 (hardware store variety).  You wouldn't want that fully assembled engine dropping on the floor -- or your foot -- would you?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Mr. P-Body on October 02, 2008, 11:52:42 AM
Craig,

   Regarding the bolt size "change"...

   '64 A-body engines had the 3/8 bolts, B-body cars still used the 7/16. It's the same "line" as the starter change from bellhousing to block.

Jim
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on October 05, 2008, 11:13:12 PM
dunno, they werent there when i repaced the main bearings and having never been in the bottom of a pontiac motor didnt know they were spose to be. long story short i noice a cut off dip stick and figure i would replace it when i was done, first time i fired up the motor it shot the new dip stick right out from under the hood.

lol, until my friend pulled his 428 apart, he had to keep a broken off dip stick in the tube while driving the car, and a complete dipstick on the shelf at home for dipping the oil...same problem, no bottom piece on the tube....lol.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 72blackbird on November 25, 2008, 12:45:53 AM
I'm overhauling/ upgrading a 350 I bought recently, and decided to mount a 4/5 windage tray on it- the lower dipstick tube is the one that has a mounting tab on it. I ordered the interference fit version (wedges between the block and tray) from Parts Industries for $19.99- thought that was expensive until I priced the OEM part at the dealer ($50).

Geno
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: MacGyver on February 16, 2009, 10:59:24 PM
The wife bought a 78 Gold Ta last year thats shes been meaning to work on... well.. after driving it until the tranny went out, its now sitting in the driveway starting its work.  This is both of our first "old" car.  Anyway, its had some extensive "rigging" in its past, so lots of baack tracking is in order for this poor car... the engine will be pulled out of it fairly shortly to give it a minor overhaul (new gaskets, clean it out, etc) where we can get a better look at the numbers, etc. as we know its not the original motor.  But from what we can see with it in the car..

481988 block casting YX code
K011 date

Which from what I can tell, is a 400, dated November 1, 1971 with 265hp... but I could be wrong as there is a TON of numbers for these engines..

So first question would be, is there anything to look out for, or make sure we do when it gets pulled and new gaskets put in to make this engine perform well?  We aren't looking to rebuild or upgrade at this time as funds don't allow right now.  Any and all info/direction/hint/etc would be helpful with this.  Thanks.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: MacGyver on February 17, 2009, 05:47:14 PM
Was out finishing the removal of the rear, and looked under the hood again, and saw a couple numbers listed on the driver side head just below the valve cover..

D <-- N  71    G070

I would imagine the D and N are for DAy and Night shift, thus being DAy shift... but the 71 and G070 haven't come up with any info yet.. I am not able to see any numbers on the pass side yet as the engine is sitting far back (only on the motor mounts) and can't see past the accessories.

And on the Driver side Manifold, there is 1 <-- 2  E197 (could be E107)

Ideas?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Clint S on February 17, 2009, 07:54:13 PM
G070 could mean G=7th month July 07  0=1970
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: MacGyver on February 17, 2009, 08:01:15 PM
G070 could mean G=7th month July 07  0=1970

Yeah, thats what we just found.. and we also found 94 on the bottom of the head near the exhaust.. which from what I have found are 1971 350 heads?!?!  Would/could this pose a problem? 

We have found LOTS of discrepencies with this car, as the driver door is different, so no codes from there, the engine and tranny are from a different car, etc.. so we are finding one thing after another that make us want to tie up and skin the previous owers and let the animals have their way with them.. .:mad:
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Clint S on February 17, 2009, 08:12:28 PM
I think 94 heads are like 96 cc so it would be fine on a 400 probably around 8 to 1 compression.  They would be a good head for a 455 8)
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 72blackbird on February 18, 2009, 01:43:42 AM
The no.491988 400 block is a good block to use for a performance buildup (thicker casting than the weaker no.557 blocks), so you're golden there. Pontiac V-8's all come from the factory with flat top pistons for the most part, compression comes from the combustion chamber volume of the heads. You're correct in your number search for your heads- the no.94's had 96 cc chambers, 1.96/1.66 valves- about 8.3:1 CR on your 400. These are decent heads for a stock motor, or even a mild build up.

I wouldn't stress out too much about the numbers deal - you can find numbers-matching cars still but you will have to pay for it unless the seller isn't aware or doesn't care.  And since the car clearly isn't a numbers matching car, it's perfect for a performance buildup.

Geno
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Rick on February 18, 2009, 08:19:33 AM
Pontiac V-8's all come from the factory with flat top pistons for the most part, compression comes from the combustion chamber volume of the heads.

One caveat there -- the 75/76 engines (at least, maybe into 77) had "chamfered" pistons in them which dropped the static compression ratio from the usual 8:1 to about 7.6:1.  The "chamfered" was basically just the outside edge of the piston which added enough end volume to drop the SCR 0.4 point.  If anyone has questions about how the two compare I can post them.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: BoDarvelle on February 24, 2009, 09:39:33 PM
There is a hint that will save you 300 bucks.

The Dip Stick on a Pontiac is installed from the inside of the block. Not from the outside after the darn engine is already installed in the car!!!!

BTW thanks to Jim Butler for making me laugh while telling me what a dumb-ass I was for not knowing that. He is one funny guy.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: MacGyver on February 24, 2009, 10:26:17 PM
There is a hint that will save you 300 bucks.

The Dip Stick on a Pontiac is installed from the inside of the block. Not from the outside after the darn engine is already installed in the car!!!!

BTW thanks to Jim Butler for making me laugh while telling me what a dumb-ass I was for not knowing that. He is one funny guy.
:confused:  You wanna run that past me again?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: BoDarvelle on February 25, 2009, 08:56:54 AM
There is a hint that will save you 300 bucks.

The Dip Stick on a Pontiac is installed from the inside of the block. Not from the outside after the darn engine is already installed in the car!!!!

BTW thanks to Jim Butler for making me laugh while telling me what a dumb-ass I was for not knowing that. He is one funny guy.
:confused:  You wanna run that past me again?

The dip sitck tube on a 455 is pressed in from the inside of the block. If you build the whole engine and install it in the car and then try to put in the tube you have to pull the pan to install the tube. :)
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: MacGyver on February 26, 2009, 08:19:27 PM


The dip sitck tube on a 455 is pressed in from the inside of the block. If you build the whole engine and install it in the car and then try to put in the tube you have to pull the pan to install the tube. :)

Ahh.. ok.. that makes sense now.  Sorry for your misfortune.. but you won't make that mistake again..
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: MacGyver on March 10, 2009, 02:21:41 PM
Well.. tore a little more into the engine and found these numbers...

481988 block casting YX code
Engine Unit Number 0079409
K011 date (Nov 1, 1971)
Engine Cast number 0234013 (above XY)
Engine VIN: 22P317551

So with the casting date, code, number and partial VIN show that its a '72.
We found the 400 found on the bottom which proves its a 400.
What does the engine cast number (0234013)and engine unit number (0079409) tell us?
And with the VIN, the 2 is Pontiac, the 2 is for 72, the P is for the plant (which one, and what did they produce.. for what cars?)

Any idea what heads would have come on this engine, as we don't believe the 94 heads came stock on it?

As said they would be good for a stock engine/mild build.. what SHOULD we be looking for in the future?

We are just trying to knock down as much about this car as possible.. just too bad we can't tell exactly what the engine came from..
Thanks everyone.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: TreySmith on July 17, 2009, 07:16:10 PM
How much HP can I safely make on my 78' 400? I want to turbo my motor, then get forged rods and pistons down the road before I turn the boost up. But completely stock what is the HP mark that I shouldn't cross?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Clint S on July 18, 2009, 07:47:14 AM
What s the block code.  Is it a 557 or a 988.  I believe no more than 500 with a 557.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: TreySmith on July 20, 2009, 06:00:50 PM
Where do I find the block code?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Clint S on July 20, 2009, 06:45:47 PM
Back by the distributor. 
http://www.yearone.com/yodnn/tech/VehicleInfoDecoding/PontiacDecoding/PontiacEngineCodes/tabid/323/Default.aspx
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: TreySmith on July 23, 2009, 06:34:03 PM
What are the "good" years for these engines? I want to make a turbo for my car or stroke it and forge the internals. Is it 70-75? I found a 74 on craigslist and want to make sure before I look at it.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Clint S on July 23, 2009, 07:06:49 PM
The 70 through 74 are the 988 codes, BUT  the 77 and 78 w72's were also 988 codes.  best bet is to look at the code.  The other thing is is that with nitrous you probably want a 4 bolt main which are sort of rare (  I think only the RA engines were, but I am no expert :-?0  on the 400's so you may want to have your block drilled and tapped and get a set of caps
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: ayers1981 on September 08, 2009, 06:59:51 AM
The 70 through 74 are the 988 codes, BUT  the 77 and 78 w72's were also 988 codes.  best bet is to look at the code.  The other thing is is that with nitrous you probably want a 4 bolt main which are sort of rare (  I think only the RA engines were, but I am no expert :-?0  on the 400's so you may want to have your block drilled and tapped and get a set of caps
I read were the w72 engine codes a 988XX.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 72blackbird on September 08, 2009, 08:32:02 AM
Pontiac switched to the lightweight 400 block design in 75- I know because I have a 75 481988 400 block, and have seen the 75 500557 block as well. Avoid the latter because it has thinner main webs and will crack if you stoke it or build it over 400 hp.

4 bolt mains are nice, but it's generally accepted that the factory 2-bolt setup will support 600 hp. You could run ARP main studs for insurance and it would be more than enough.

Geno
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: J-Force on December 07, 2009, 11:35:46 AM
Hi, thought I'd post two quick questions in this thread since I'm rebuilding a 73 455 trans AM.

1) I have steel headgaskets that require copper coat on the steel side (block side).  Any suggested alternatives since copper coat is not readily available in my part of the world?  what would happen if i didn't coat the gaskets?

2) does anyone know where you can get 4spd shift linkage parts....specifically those rubber grommets, clips, and other linkage assembly fasteners?

Thanks for your help
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 72blackbird on December 10, 2009, 01:13:14 AM
Why are you using steel head gaskets? I would use the gaskets that each manufacturer recommends for their aluminum heads, but if you're using iron heads get some Fel-pro's (permatorque blue) and be done with it.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: koury73 on February 18, 2010, 06:47:03 PM
does anyone know where you can get motor mount brackets for a 70-74 trans am??   I need the ones that bolt to the subframe
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 72blackbird on February 26, 2010, 05:31:06 PM
Try Rock Auto- I've heard they still stock that bracket.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on March 30, 2010, 09:55:23 AM
Building up a 1968 400 that I am going to be putting into my 1977 TA S/E. The original engine was destroyed. My question is on what cam to put into this engine. I am running stock pistons and stock heads. I am doing a full restoration on a TA SE Bandit. I am not making this a daily driver, but I do want it to take off when I stand on it and still be able to use pump gas. I am hoping to get close to 375-400 ponies out of it. I am looking at the Summit SUM-2802 cam. Suggestions?? Mike/KD9RG
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Mr. P-Body on April 01, 2010, 07:14:35 AM
Mike,

   WHICH '68 400? Head casting number?

   400s of the era are "high" compression compared to the later ones. Changes must be made to make the 10.5:1 engine "pump gas friendly". The practical limit for iron heads is around the 9.5:1 range.

   Tell us as much as you can about the engine. Also know that there's a bracket mounting hole "missing" on the '70-older heads that's needed for the alternator/power steering bracket. There's a simple "fix", but be aware.

   Summit cams are "generi-grinds", meant for ease of ordering. They are not "optimum".  Once we know more about your engine, we can make a solid recommendation for a cam that will meet your performance requirements.

Jim
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on April 23, 2010, 01:05:31 PM
 Looks like it is 16 which links it to the 68/69 400 HO heads they were made in Feb 68.
 
Block is marked YT with a casting number of 596085. I believe they are the stock pistons, but I am not positive. The Pontiac guru I got them from said they were stock.

  Looking at a Lunati cam PN 307A2LUN. Gentleman that I spoke to there recommended that I use a thicker head gasket to help reduce the compression.

Sorry for taking so long to reply. There is an impeding high school graduation in my house and the "honey do" list has gotten out of hand, so the car has been ignored. Told her I was working on the engine this weekend so chill out. Ha....of course I'll pay for that later. Mike/KD9RG
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on April 25, 2010, 08:57:59 AM
I ffigured  you guys would be full of opinions on this one. No comments? Btw, I was wrong about the block casting number it is 9790077 or the last digit could be a 1. Mike/KD9RG
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Rick on April 25, 2010, 04:41:02 PM
From the sound of things, it looks like your static compression ratio is about what it was from the factory for that engine, which is too high for use with today's pump gas.  I'm not sure you can play enough games with the head gasket to reliably drop the CR to the 9.5:1 range you need for pump gas.  The sure-fire way to get there is to have reliefs milled into the pistons to ensure you increase the end volume enough for the drop in CR you need.

Another important bit of informaton re: cam selection is what your rear gears are going to be, as you want the cam to match up with those on a street car.  Ideally you want the torque peak at or slightly below your highway cruise RPM.  An engine for strip use is another matter altogether, as you'll be revving it much higher in order to make as much HP as possible.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on April 25, 2010, 04:43:20 PM
Running 3.55 in the rearend. I was a little concerned about the compression ratio. The folks at Lunati did ask me all the questions that I would expect, to be able to answer my question as to what cam they would recommend. I'm am really struggling with what to do. The opinions are all over the place. Mike/KD9RG
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 72blackbird on April 25, 2010, 07:48:41 PM
If you're gonna 'ride the razor's edge' and run heads that will give you more than 10:1 SCR, you better run a cam that has more than 230 degrees @.050 to bleed off some of that compression. Even that is no guarantee you'll lower your DCR enough to be safe for pump gas, but in most cases it works. For all practical purposes 9.5:1 is the limit for pump gas.

Are you talking about the Lunati 30702?

Geno
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on April 26, 2010, 05:00:06 AM
The number the Lunati guy gave me was 307A2LUN. Which one is better? Looks like the 307A2LUN meets your 230 degree requirement. Mike/KD9RG
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on April 26, 2010, 10:04:53 AM
Btw, there was an earlier comment about a missing mounting hole and known fix for that issue. What is the fix? Thanks MikeR.

Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: SolarGold78 on April 27, 2010, 01:50:44 PM
I am using 1968 #16 heads on my 400 with a Comp Cams 268H. I also have had the Q-Jet calibrated for my set up. I have no trouble running it on 93 octane unleaded. I am running about 38 degrees total mechanical advance + the vacuum advance. My gearing is 3.41:1. Hope that helps.

I fixed the missing mounting hole by welding a nut on the back of the bracket for the alternator swivel bolt. That bracket is solid enough and bolted down in enough places that it works fine.

ZDDP additive is a must with each oil change.

-Chuck
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on April 28, 2010, 06:13:34 AM
I knew somebody out there had to be running this setup and I was hoping to find them. You have made my day Chuck. Thanks!!!! Mike/KD9RG
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on August 30, 2010, 06:24:04 AM
Hey Chuck, did you change the valve springs or did you use the original ones.  I am still trying to decide which cam to go with...looking at the Comp Cam 268H that you used and the Lunati 307A2LUN. Since your using the 268H and not having any issues I am really giving it a lot of consideration. Do you have the complete part number that you installed? Trying to get this engine assembled (it is now in a storage unit with the car) Before winter so I can move the engine to a heated building. Finally getting back to the project after a couple of months off and a removal of a wife. Mike/KD9RG
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: SolarGold78 on September 29, 2010, 01:14:48 PM
Mike,

Sorry I didn't see this sooner. Here is a link to the kit.

http://www.compperformancegroupstores.com/store/merchant.mvc?Store_Code=CC&Screen=PROD&Product_Code=K51-232-3 (http://www.compperformancegroupstores.com/store/merchant.mvc?Store_Code=CC&Screen=PROD&Product_Code=K51-232-3)

-Chuck
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on October 27, 2010, 07:50:16 PM
That is the kit I ordered and installed. Thanks


Mike,

Sorry I didn't see this sooner. Here is a link to the kit.

http://www.compperformancegroupstores.com/store/merchant.mvc?Store_Code=CC&Screen=PROD&Product_Code=K51-232-3 (http://www.compperformancegroupstores.com/store/merchant.mvc?Store_Code=CC&Screen=PROD&Product_Code=K51-232-3)

-Chuck
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on October 27, 2010, 07:52:31 PM
Chuck, What intake and carb are you using? I want to put the same  on my motor. Who calibrated the carb? Mike/KD9RG



I am using 1968 #16 heads on my 400 with a Comp Cams 268H. I also have had the Q-Jet calibrated for my set up. I have no trouble running it on 93 octane unleaded. I am running about 38 degrees total mechanical advance + the vacuum advance. My gearing is 3.41:1. Hope that helps.

I fixed the missing mounting hole by welding a nut on the back of the bracket for the alternator swivel bolt. That bracket is solid enough and bolted down in enough places that it works fine.

ZDDP additive is a must with each oil change.

-Chuck
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: SolarGold78 on October 30, 2010, 07:45:52 AM
Chuck, What intake and carb are you using? I want to put the same  on my motor. Who calibrated the carb? Mike/KD9RG

Mike,

I have an Edlebrock performer and a Quadrajet. I got the carb kit from HO Racing Specialties. You give them the specs of your engine and for $75 you get all the parts you need to set the carb up and a very detailed instruction book. http://www.horacing.com/ (http://www.horacing.com/)

-Chuck
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on October 30, 2010, 09:45:55 AM
THanks for the info. I have to ask what could be a stupid question, but its really bothering me. You did not have any issues with the shaker did you? With my block being from a 1968, I am having to us a engine mount adapter from Classic Industries (https://www.classicindustries.com/firebird/parts/c269513.html). They assured me that I will not have any Shaker issues.
I am finally get back on the car. A divorce in the middle of a restoration is not a good thing. Car is totally disassembled, no front end or frame on it. Only thing left on the car are the doors and the truck lid. The rear axle has already been rebuilt and is back on the car. Body is going to be soda blasted in the next week or two and then it goes to my sons to be primed and painted. Trying to get engine closed up and will move it to a warm location for the winter. I have the cam and heads on it. Need to finish installing the push rods and rockers on one side and then I will be ready to put the valve covers on. Currently the whole nine yards is in a storage building. Frame, front suspension parts, hood hinges and other small items have been powder coated and are ready to be mounted back on the car. I have had enough of dis-assembly, dying to start putting this puppy back together. I have about 90% of the new parts I need to reassemble. Heading to Ft Myers in 2 weeks and I think I am going to drive over to Miami and visit Rick at Trans Am Specialties just to chat and take some pictures of a reassembled car. I am not to locked up about being totally accurate with the engine just due to the fact that it is not the original engine. I want to get it close but I am more concerned about it running good and the shaker being in the right place. Thanks again. Mike/KD9RG
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: SolarGold78 on October 30, 2010, 08:11:35 PM
As long as the engine sits in the stock position the shaker will be fine. I figure you have them, but you also need the correct air cleaner base and shaker for a 400.

-Chuck
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on October 31, 2010, 08:00:22 AM
Yep, have all the shaker parts.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on November 17, 2010, 05:58:24 AM
Chuck, What size/number is the quadrajet?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: SolarGold78 on November 22, 2010, 11:40:13 AM
Chuck, What size/number is the quadrajet?

I'll have to look for the number, but it's the one for the 180hp Auto.

-Chuck
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on November 23, 2010, 05:03:25 PM
Wow. That is surprising. I figured your running a lot more ponies than that.  Its been a long time (28 yrs) since I have done any hot rodding,  I figured you were closer to 400 hp.  Am I the bonehead here for missing the obvious?  Mike/KD9RG
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: SolarGold78 on November 27, 2010, 06:58:22 PM
Wow. That is surprising. I figured your running a lot more ponies than that.  Its been a long time (28 yrs) since I have done any hot rodding,  I figured you were closer to 400 hp.  Am I the bonehead here for missing the obvious?  Mike/KD9RG

Mike,

:) The engine in its current form is around 400HP. I figure about 370 or so with the exhaust in place. The quadrajet I'm using is the one from the car's original 180HP engine. Come to think of it that carb is almost all that remains of the original engine. With the proper tuning it is more than capable of feeding a 400HP 400. You aren't a bonehead I just didn't explain clearly.


-Chuck
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: red79phoenix on January 07, 2011, 11:11:58 AM
Im looking to buy these parts from a member possibly I just need to know if you guys think these parts are any good. If the cam is any good what heads would work good with it?

http://www.summitracing.com/parts/SLP-411NP30/

here are the rods:
http://www.jegs.com/i/Eagle/356/CRS6625PP3D/10002/-1

and the cam:
http://www.jegs.com/i/Crane+Cams/271/105082/10002/-1
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Mr. P-Body on January 13, 2011, 12:17:53 PM


   The rods are good ones if sticking with Pontiac parameters.

   The pistons are stock-replacement "fits all". They have 8 valve reliefs to accomidate both early and late valve angles. Not suited for performance, but fine for a stock "driver".

    Crane cams are obsolete. Nothing new for the Pontiac in many years.

FWIW

Jim
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: red79ta on January 31, 2011, 09:41:31 PM
Many people say 400ci and up is a big block. The only TRUE small block Pontiacs are the 301's and 265's. The block is literally smaller! Anything else 326-up is all standard size. but the 301 is not really a motor worth writing this post about either...they are good for giving people something to blow up in their spare time.  :P
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: tajoe on February 05, 2011, 01:58:36 PM
C'mon now Red, don't jinx me with 301 bashing, we all know the motor has it's place, and will agree it's not racing. But I wanted to keep this thread going, and ask this question. Does anyone know the exact yr and why Pontiac changed the flywheel hole diameter, at the back of the crank? Somewhere in 74, 75, or 76. I've only had stick cars, and the early 70s and before w/ the 10 1/2" clutch is a different F/W,( bore diameter) than the 11" on my W-72. I'm assuming the flexplates are effected by this too.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: red79ta on February 06, 2011, 10:01:47 PM
C'mon now Red, don't jinx me with 301 bashing, we all know the motor has it's place, and will agree it's not racing. But I wanted to keep this thread going, and ask this question. Does anyone know the exact yr and why Pontiac changed the flywheel hole diameter, at the back of the crank? Somewhere in 74, 75, or 76. I've only had stick cars, and the early 70s and before w/ the 10 1/2" clutch is a different F/W,( bore diameter) than the 11" on my W-72. I'm assuming the flexplates are effected by this too.

It changed over in '76. It was used as one of the ways to save weight. smaller weaker flywheel, along with weaker engines after 1974. They had their prime in the late 60's early 70's, but they slid downhill after 76 by offering the olds 403 in 1977, and other things began to lighten up as well. 
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: tajoe on February 07, 2011, 06:44:47 PM
Thanx for clearing that up Red, and i agree with your opinions.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: badmonkey on March 10, 2011, 07:12:11 AM
You guys must stop stating 9.5:1 is a flat maximum for pump gas and iron heads. Because that doesn't account for elevation. Up here at 4500', I could run 10.4:1, and still have a hair less cranking compression than your 9.5:1 at sea level.
 
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on March 10, 2011, 11:53:48 AM
True...just don't drive down hill to the bottom....lol. :lol:
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: tajoe on March 11, 2011, 05:23:21 PM
True...just don't drive down hill to the bottom....lol. :lol:
LOL!!! (hey Leigh. Did you say that with an accent?)
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on March 12, 2011, 04:54:22 AM
I don't have an accent....its you guys that sound strange....  :lol: :lol:
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Robbie.McKinney on July 13, 2011, 01:53:43 PM
I have a 1976 TA 400 and it has like no power what so ever can't even spin the tires I was at a car show and a guy told me that you could bypass the main vaccume line directly to the carb has anyone else heard of this?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Clint S on July 13, 2011, 06:16:48 PM
Have no clue as to what that would be as a vacuum line would have nothing to do with power output from the engine aside from the advance canister or a leak.   Always remember, many people at car shows  really have no clue.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Robbie.McKinney on July 13, 2011, 10:09:19 PM
Have no clue as to what that would be as a vacuum line would have nothing to do with power output from the engine aside from the advance canister or a leak.   Always remember, many people at car shows  really have no clue.
that may be true but i still dont see why such a big engine seems to have no power what so ever maybe i need to rebuild the carb or something  :?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Grand73Am on July 13, 2011, 10:31:16 PM
It's possible that the vacuum advance on your distributor is connected to ported vacuum on your carb. If so, by connecting the distibutor vacuum advance line to a manifold vacuum source instead, you'll have more power. By doing that, your idle speed will increase, so you'll have to adjust your idle screw down a bit. That would be an easy and free thing to look at and try.
If the speed doesn't increase when switched from ported to manifold vacuum, your vacuum advance is most likely bad, so would have to be replaced.

Also, your timing may not be set correctly, so check that with a timing light, with the vac advance line disconnected and plugged at the vac source, which is another basically free thing to try.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: bentley26 on August 08, 2011, 09:20:51 AM
New '73 455 owner here... Still trying to learn all of the history and technical tricks associated with the car.  One thing I was curious about... Due to the OPEC embargo of that year, the '73 TA engine was "de-tuned" to meet new federal emissions and efficiency requirements.  True?  If so, any suggestions to re-tune the engine to boost performance a bit without ruining the integrity/originality of the vehicle?  Thanks!
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Grand73Am on August 08, 2011, 06:13:02 PM
73's weren't really de-tuned due to the 73 opec embargo, because the embargo happened during 1973. The 73 models were already being produced, delivered and bought in the fall of 1972, before we knew there would be a gas shortage in 1973.

Increased emission regulations meant a drop in the compression ratio, down to 8.0:1, losing 50 hp from the previous year.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: KD9RG on August 31, 2011, 05:46:47 AM
Chuck, your not gonna believe this, I have the car back out and have started the restoration again. I went to put the new Edelbrock intake manifold on the engine last night.........they sent me the wrong one!! I  have had it for a year, can't find the invoice and for the life of me I can't remember who I bought it from. Unbelievable. Did you happen to make it to the Nationals last weekend? I was there Saturday. Mike/KD9RG




Chuck, What intake and carb are you using? I want to put the same  on my motor. Who calibrated the carb? Mike/KD9RG


Mike,

I have an Edlebrock performer and a Quadrajet. I got the carb kit from HO Racing Specialties. You give them the specs of your engine and for $75 you get all the parts you need to set the carb up and a very detailed instruction book. http://www.horacing.com/ (http://www.horacing.com/)

-Chuck
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Grandvillebob on February 05, 2012, 10:45:58 PM
I have a set of heads that I bought off a guy not too long ago, and have seen several people with them on 455's making big horsepower, and cannot figure for the life of me how.

When I first got them he told me they were RA/IV heads, but after digging into them, I actually believe they are rarer that those.  They are 197 heads, but, they are stamped on the end with "nunzi" meaning that he ported and polished them.  I had new SS valves with 30 degree stems, and three angle valve job, and the springs set up for a hydraulic 550-600 lift cam, but when I went to figure out compression, they are 111 cc's.  Can anyone tell me how people are getting horsepower from them since no one making a domed piston, without a special molding of your chambers?  I have a small fortune in them, with a ported and matched torker 2, and I saw a guy selling bare casting with "some valve and springs" and he wanted $2500 and have not heard of many people using them.  They are listed as 1971 455/335 hp heads.  Please enlighten me to some wisdom?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: chief poncho on February 06, 2012, 01:47:04 AM
They are '71 455 HO roundport heads, based on your description.  If Nunzi ported them, they are probably good for 450+hp with the right cam selection, headers and proper tuning.  Keep in mind, people made terrific power with the SD heads and they have the same big chamber volume as the HO heads, but flow a bit better.  Basicially what you have is one of the better factory heads Pontiac ever made.  When you say big hp numbers, how big are you saying?  Lower compression does not have to mean low power.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: critter on February 06, 2012, 09:56:32 AM
And if you contact one of the major Pontiac vendors you can special order a mini-dome piston from companies like Ross. Call Butler. They can help. With Nunzi's touch porting and some compression 500hp is very doable.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Grandvillebob on February 06, 2012, 10:17:33 AM
Thanks guys, Butler you say huh?  I have been looking in JE Piston catalogs and such, never thought of them. The guy I saw was using these heads was making 510hp on a dyno.  I have a block for them, it is a 69 428 block, bored 060, with a balanced 455 crank and rods.  It has no 62 ported heads on it now and is 11-1 compression and has a 648/655, 308/310 cam in it...way too much for the street, but would like to put a domed piston and these heads and the manifold on it and a smaller cam for a high hp street motor in a 75 trans am I have. 
By the by critter, love the t-shirt is now a rag line...feel the same way myself.
Looking forward to hanging out here a little, thanks for the reply guys
Grandville

Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Grandvillebob on February 06, 2012, 08:58:41 PM
Well, I do believe I have figured out how to get pics on the photobucket site, here are some pics of the trans am and one of the parade queen..enjoy! :-P
http://s1145.photobucket.com/albums/o516/GrandvilleBob/
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: critter on February 06, 2012, 09:23:17 PM
I do like a girl with a big butt! Nice GrandVille. I've driven them and almost bought one but it was 1979 and I couldn't afford the gas at the time. I'd love to take one, drop the top and spend about a month driving out west to check out the Grand Canyon and up to the Tetons and Yellow Stone.
Title: 76 400 (re)build
Post by: TransAm_Stan on February 27, 2012, 05:27:42 PM
Hi guys!

I need some help on a plan of attack on this engine rebuild.  The motor was rebuilt in 96.  Very few miles were put on this car after the rebuild.  Good thing too. After I pulled a main cap, It looks like someone forgot to polish the crank.  I have not driven this car. 

Here is the particulars as it stands.  The block & crank is going in tomorrow for its "check up"..

Block:   500557
Heads:   6X
Cam:   Edelbrock 2157
Pistons: 2512P chamfered edge std. bore
Intake:   Edelbrock Performer
Carb:   Edelbrock
1.5 roller rockers
ARP rocker studs
Dbl. Roller chain
Manual Tranny
3:73 rear end (unconfirmed)

I will be adding....(at least)

Tribal Tubes Tri-Y's
Pypes tranverse exhaust (2.5)
Q-Jet rebuilt by the "Bandit"

I guess the Q's center around what performance can I expect out of this set up?  And since I am in further than I wanted to, what, if any, different parts would you recomend for a nice running semi-weekend cruiser? (I would love to have a lopey idle!) Also what rebuild kit do you suggest?  I see Summit has Sealed power (Federal Mogul) kits.  I am kind of clueless here...

I do have Rocky's "How to rebuild Pontiac V8s". I just want some "real world" opinions...

Thanks!

Stan
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: critter on March 02, 2012, 09:48:06 PM
I'm guessing the 557 block is the later 400 ci? If so, most of the components you have work but the switch to the Qjet is a great idea. I'm no fan of Edelbrock carbs. And I'd suggest having the heads lightly ported and moving to a came with roughly a 230/236 duration for that lope and still having the vacuum you need for accessories.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 78TransAm on March 04, 2012, 02:58:30 PM
I'm guessing the 557 block is the later 400 ci? If so, most of the components you have work but the switch to the Qjet is a great idea. I'm no fan of Edelbrock carbs. And I'd suggest having the heads lightly ported and moving to a came with roughly a 230/236 duration for that lope and still having the vacuum you need for accessories.

I am glad I sat down and read through this thread today. I got my motor hoist this week and am getting ready to pull the motor out of my 74 Trans Am and I have been giving some motor some thought. Unfortunetely the original 455 was not in my 74 when I bought it. The motor that is in it is a 75 400 YT 500557 casting. I have been set on getting rid of this motor and locating a 455 for it, but then I was giving thought to what kind of horsepower and durable motor could I build with the 75 400 that is in it.

Now I read a couple post that say to avoid the 500557 casting because they have thinner castings to save weight and can crack with excessive power or installing 4 bolt mains. I would like to build a somewhat powerful engines, So with that being said would the general consensus be to plan on sticking with my plan of finding a 74 or earlier 455 or 400 block and just scap this one?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: critter on March 04, 2012, 04:58:25 PM
It depends. What's the HP/torque goal? The 557 isn't the best but it's not junk either.

That said, good castings for 400s are common and the odd 455 still turns up around my neck of the woods. I think I'd give it serious thought if I was making 400HP or better.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 78TransAm on March 04, 2012, 06:29:39 PM
It depends. What's the HP/torque goal? The 557 isn't the best but it's not junk either.

That said, good castings for 400s are common and the odd 455 still turns up around my neck of the woods. I think I'd give it serious thought if I was making 400HP or better.

I am thinking it best that I continue to look for something else. I also read Rocky's section in his book about the cons of the 557 castings. I want at least to be in the neighborhood of 400 HP.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: falcon4 on March 04, 2012, 06:32:14 PM
Quite soon, I'll be pulling the tired old 403 olds and TH 350 out of my '76 T/A and replacing it with a nicely warmed up Y-4 455 and TH 400.   I'll need to replace the transmission crossmember and shorten the tail shaft.  Will a '70 - '74 turbo 400 cross member fit onto a '76 subframe?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on March 07, 2012, 06:44:04 PM
The 70-74 crossmember bolts in further back on the rails, you'll have to drill new holes in the rails to bolt to. I doubt you're running the converter (lol) so that won't be a clearance issue.
If you need the measurements, I have an early frame here that I can take the measurements off.....I had to do the same thing to my 71 as it has a 75+ frame in it....and I found you cannot run the 75+ crossmembers with an early body floorpan...they do not fit.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: falcon4 on March 07, 2012, 06:56:04 PM
Yes Leigh, Please post dimensions.  I'll only be running headers of cause... 8-) 8-)
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on March 07, 2012, 07:06:26 PM
When the rain stops, I'll go out and measure it....man, its been raining here seems like forever!
Title: Which Cam for my 1978 W72
Post by: Blondylab on May 22, 2012, 05:44:40 PM
I'm in the process of rebuilding my 1978 W72 with Super T-10 and 3:42 gears. The car will only be used as a street cruiser, so I'm not looking for any monster HP here. The block is stock bore so I'm using all the original bottom end stuff, new bearings, rings, frost pulgs, etc. The exhaust will be long tube headers, 2.5" with an X pipe and # 17219, 14" Dynomax mufflers. Heads will be shaved .020" to increase the compression a little. The Q-Jet is stock, but will be rebuilt with a Cliff Rutters kit. The machine shop guys are recommending the XE250H Comp Cam, which is 206/212 with a LSA of 110", verses the original 192/210 with LSA 113.5". Just wondering if this is the best choice for my build.

I'm no expert on cams, so any opinions would be greatly appreciated  :-D
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: GM4LIFE on September 11, 2012, 02:11:16 PM
Which Trans Am is faster stock, 1976 455 4spd or 1979 400 4spd?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: TripleTransAm on September 11, 2012, 04:01:45 PM
uh oh...
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Ben on September 11, 2012, 08:04:48 PM
Depends on the driver!
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: cpgta on September 19, 2012, 03:57:09 AM
I just bought my 1st Trans AM. I'm getting ready to pull the motor to rebuild it. I've been doing some research but I'm not sure how to tell if I have 400, 403, or 455. how can I find out?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on September 19, 2012, 04:19:33 AM
If its a second gen T/A, you can look on the sides of the block - the capacity is cast onto the block. 403 is distinctive in that it has an oil filler tube sticking up at the front of the engine.

If its a Pontiac engine, then you can further ID it by -

The casting number for the block is on the block upper surface, behind the passenger side head....you need a flashlight and maybe a mirror to read it in the car, but its easy once its out.
Take down that number, and then look for the two letter (possibly three) code stamped near the engine number on the flat of the block under the front of the passenger side head.

Now that you have these pieces of information, the only other thing you need to know the complete story on the engine is the date code of the casting, which is located near the distributor hole at the rear of the block....it'll look something like C154.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: cpgta on September 19, 2012, 04:56:01 AM
thank you for the info..
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: zippy on October 21, 2012, 12:24:41 PM
The 70-74 crossmember bolts in further back on the rails, you'll have to drill new holes in the rails to bolt to. I doubt you're running the converter (lol) so that won't be a clearance issue.
If you need the measurements, I have an early frame here that I can take the measurements off.....I had to do the same thing to my 71 as it has a 75+ frame in it....and I found you cannot run the 75+ crossmembers with an early body floorpan...they do not fit.

Your back body mounts lined up???  When I put a Pre 75 Sub in my 81, I had to cut and reweld the back of the  subframe 3/18" shorter as the Pre 75 didn't have Cat's so the frame rails were longer.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on October 21, 2012, 02:42:36 PM
I had both early and late frames sitting side by side when I checked things out. They are the same dimensions - the rails are the same pressings. The rail pressings are slightly different where the rear mounts are on the late frame, but other than that, they are identical.
The rear mounts require that you cut them to suit the year of the body vs the year of the subframe - I am running a late subframe under a 71 body, therefore I had to cut new holes further back on the rails.

(http://i104.photobucket.com/albums/m195/TA76400/71%20Firebird/earlyrearmountholes2.jpg)

I then had the old mount holes plated over.

(http://i104.photobucket.com/albums/m195/TA76400/71%20Firebird/oldmountsplated.jpg)

The frames are the same width and the same length. The early gearbox crossmember bolts into the depression in the tops of the rails on each side, the late crossmember bolts onto the tops of the rails forward of the depression.
You cannot use the combination of a late gearbox crossmember under an early body....there is insufficient floorpan clearance above the rails for the crossmember to fit. A 74 or earlier body requires the use of an early crossmember, regardless of the year of subframe used.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: zippy on October 21, 2012, 07:04:38 PM
That's weird.  My present subframe is from a 75 Camaro on a 81 tub.  I never thought of redrilling  LOL,  I'm sure I had to cut the rails and shorten them for some reason.  Hit the floorpan maybe it was?  That was 8 years ago LOL.  But I do remember cutting 3 1/8" out and rewending the rear portion back.  Maybe I just never thought of drilling, was to focused on cutting?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on October 22, 2012, 12:18:41 AM
Strange...a 75 Camaro frame (suits a cat converter car) should fit under an 81 body with no mods at all.

I know I had not only the 71 frame, and the post 75 Camaro frame, but I also had a 79 Firebird frame....all at the same time and there was no difference in anything I could measure except for the rear body mounts, the crossmember location and the size of the holes for the lower control arm bolts.

Hey...you sure that was an F-body you were bolting that frame under?????   :lol: :lol: :lol: :lol:
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: zippy on October 22, 2012, 05:23:20 PM
Somewhere I got the measurements on my comp still I think, for the subframe.  Mines pulled out right now,  Buildin another 455. So I'll measure
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: BlueTTA on December 07, 2012, 07:17:52 AM
Hi guys and gals!  I have a question about a 78 TA with a 400 and I don't have access to my manuals right now, so I thought I'd give this a try.

I'm looking into purchasing a 78 Y88.  It's kinda trashed, but I'm not worried about that too much.

What I need to know is, "What was stock, as far as emissions stuff goes, for the 78 400?"  and "Did it have a cat, and if so, one or two?"

Also, does anyone have a photo of the emissions sticker, so that I can tell what is missing when I go to look at it?

Thanks,
Chris
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Grand73Am on December 07, 2012, 07:25:55 AM
From your signature, it looks like you have a 79. The 78 has the same kind of emissions as a 79. One cat. None of these cars came with 2 cats. And an EGR valve.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: BlueTTA on December 07, 2012, 07:40:28 AM
My 79 is a California emissions 403, and my 80 with the 400 doesn't have any smog equipment on it. 
So I can't use either one as a reference.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: johnnys81t/a on December 09, 2012, 02:58:56 PM
Thought a sub thread would be good for motor specific questions. We'll see how it works out. Sticky for now. Have fun with it guys.
TOM
i have a 455 pontiac engine with 76 6h heads..its all stock...how can i tell what compression ratio it has?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: chief poncho on December 10, 2012, 01:39:58 PM
If its completely stock with 6h heads its factory rated to around 7.6:1. 
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: NCBadBird1979 on January 20, 2013, 01:15:04 AM
Question: I have a '75 Pontiac 400 motor that had the Quadrajet removed and replaced with a Holley. I want to put a Quadrajet back on it but I don't know what size (length/thread size) the four mounting bolts are suppose to be. I know the two front bolts are a different size than the two rear bolts. Does anyone have any measurements of the four bolts?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Ben on January 20, 2013, 11:07:37 PM
Does anyone have any measurements of the four bolts?
Don't have the thread counts, but if you want a set of bolts go down to your local AutoZone and order Edelbrock part #1925 - it's the correct quadrajet bolts with washers and everything.  Only like $13.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: krhsierra on August 24, 2013, 12:10:53 AM
Hello! I have a 79 olds built 403 that i need to put into a 73 pontiac 455 so i can rebuild the 455. Will the 403 drop into the 455 easily or will i have problems lining up the motor mounts? Sorry, both are Formulas.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 1blk1 on August 24, 2013, 12:15:04 AM
can be done but sure not easy
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: krhsierra on August 24, 2013, 12:22:27 AM
Not easy? I should have known. Can you elaborate a little bit please? I have to know what to expect before i do this. Thanks for your input btw! Greatly appreciated
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Clint S on August 24, 2013, 06:18:52 AM
Not easy? I should have known. Can you elaborate a little bit please? I have to know what to expect before i do this. Thanks for your input btw! Greatly appreciated

We (I) need a more clear  picture from you.  Assuming the engines a 79 403 and a 73 455?   Is  the car a 73 Formula?   It will fit just fine.   Battery in olds and pontiac on opposite sides, starter on opposite side.     Engine mounts are the key here.  If it is a 79 car just need to get the correct mounts for that year olds for the engine.    If it is a 73 car  the car side mounts will have to be changed to the clamshell kind.     
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Grand73Am on August 24, 2013, 10:02:30 AM
Starter actually is on the same side for Pontiac and Olds, so that's one less thing to worry about  :-) . Fuel pump is on the opposite side though, but just run a fuel line to it.

But yes, the engine mounting will be an issue. You'd need some Olds 403 engine mounting brackets from a 403 that was in a firebird/TA, since no other brackets from another car will fit. Then you need some 79 Olds 403 "clamshell" type motor mounts to bolt to the frame. I don't know if a 73 frame has the right holes for the clamshell motor mounts, so you may have to drill some, once you determine where they need to go.

Then of course, all the pulleys and accessory brackets, distributor, are different, so hopefully your 403 engine is complete with those things on it. Air cleaner will be different too for an Olds.

Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 1blk1 on August 24, 2013, 11:21:08 PM
Fuel pump is on the opposite side though, but just run a fuel line to it.
But yes, the engine mounting will be an issue. You'd need some Olds 403 engine mounting brackets from a 403 that was in a firebird/TA, since no other brackets from another car will fit. Then you need some 79 Olds 403 "clamshell" type motor mounts to bolt to the frame. I don't know if a 73 frame has the right holes for the clamshell motor mounts, so you may have to drill some, once you determine where they need to go.
Then of course, all the pulleys and accessory brackets, distributor, are different, so hopefully your 403 engine is complete with those things on it. Air cleaner will be different too for an Olds.

like I said
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: krhsierra on August 25, 2013, 01:30:22 AM
Sorry, let me clear this up. Its a 1979 formula with the olds built 403. I want to put it in a 1973 formula 455.  Im going to have the 455 rebuilt, but in the meantime im going to put the 403 in. I know its alot of work, but the 79 needs too much work done on it to keep it on the road. the motor is fine but everything else needs work.  The 73 is fine except for the motor. Plus theres a smog issue for the 79.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on August 25, 2013, 02:08:46 AM
As Steve said (above), I believe you'll have to drill some holes in the crossmember for the later clamshell mounts......you can make a template off the 79's frame as it will have early and late pattern holes in it.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: krhsierra on August 25, 2013, 04:48:16 PM
Ok! Thanks for the input! By the way, Leigh, your 455 is beautiful!
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: LeighP on August 26, 2013, 12:56:53 AM
 :grin: thanks.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: casey1 on September 19, 2013, 01:28:43 PM
iam in the market for a flywheel for a 76  400 this motor takes the bigger center hole (2.75'') so i believe . all the others ive tried barely fit on an the hole do not line up. not sure why they have to be in the $300 dollar range .
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Smokedbird on August 31, 2015, 07:11:33 AM
Hello guys,
I have a 89 TA with a stroked motor.
Is the firing order the same with the 400 crank as most 350's ???
Thanks
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: nhirschi on September 18, 2015, 12:54:45 PM
question.im interested in putting an olds 455 in my 79 firebird,but would a 454 be a better engine in general and for getting parts.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: chief poncho on September 18, 2015, 05:42:07 PM
Better is a relative word.  Parts for a big block chevy (BBC) are generally more readily available and cheaper than a Buick, Olds or Pontiac (BOP) engine.  However, today's aftermarket is really strong allowing BOP engine builders lots options.

Why not go with a Pontiac 400 or 455 instead of an olds 455? Depending on the level of build, the Poncho mill probably wouldn't run much more than a similarly built BBC.  Honestly if you're open to other alternatives, an LSx conversion would probably make the most sense.  While it will require a bit more work, you end up with a modernized combo that will give you better power options, driveability and fuel economy. 
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: EvilEdOlean on October 07, 2015, 10:16:34 AM

Posted - 05 Oct 2015 :  08:58:52 AM  Show Profile  Email Poster  Edit Reply  Reply with Quote  Delete Reply
Finally got me an engine cylinder compression tester and tested
Compression in each cylinder. Below results show the cylinder # Dry and wet test readings
1 D 141 W 185
3 D 132 W 162
5 D 130 W 225
7 D 141 W 230
2 D 137 W 195
4 D 81 W 129
6 D 30 W 42
8 D65 W 100
Could be a bad head gasket on the driver side block, three cylinders on the same head 4,6,8 with low compression and the middle one the lowest and worst. Wet test on #6 should have been higher also. This may also explain why the radiator water was bubbly the second time I started the engine and did not look right. I think the engine overheated and blew out. Looks like I'm gonna be taking the passenger side Cylinder block off. Oh what fun, I not done this since 1980. Maybe next weekend.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: EvilEdOlean on October 11, 2015, 10:16:46 AM

Posted - 05 Oct 2015 :  08:58:52 AM  Show Profile  Email Poster  Edit Reply  Reply with Quote  Delete Reply
Finally got me an engine cylinder compression tester and tested
Compression in each cylinder. Below results show the cylinder # Dry and wet test readings
1 D 141 W 185
3 D 132 W 162
5 D 130 W 225
7 D 141 W 230
2 D 137 W 195
4 D 81 W 129
6 D 30 W 42
8 D65 W 100
Could be a bad head gasket on the driver side block, three cylinders on the same head 4,6,8 with low compression and the middle one the lowest and worst. Wet test on #6 should have been higher also. This may also explain why the radiator water was bubbly the second time I started the engine and did not look right. I think the engine overheated and blew out. Looks like I'm gonna be taking the passenger side Cylinder block off. Oh what fun, I not done this since 1980. Maybe next weekend.

]Well got the passenger side head off yesterday, the number 8 and 2 piston were both hitting the combustion chamber on the head. Can anyone tell me how this can happen? I am assuming bad rod bearings or crankshaft bearing? I brought each piston to TDC and pushed down on them, Hearc a click when i pushed down but it did not appear to be any major gaps. Will pull off the driver side today to see if I have any of the same damage over there. Pushrods and valves all looked good. Number 8 cylinder chamber has some deep groves the head underside some deep pits now, At lease I know know have the 6x number 4 heads, if they are salvageable that is not known. Wish I knew how to post pictures here?

Link to photos below!!!!
http://s989.photobucket.com/user/Edward_Ozogar/library/
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 77TAfromMO on March 17, 2016, 06:39:14 PM
So a local engine builder I know has a 1971 455 engine that I am going to go have home build. Crank condition is unknown so but the time mag it and do any other work I we can buy a new forged crank. Since price does not seem to vary much between stroke lengths considering maybe going as up to 4.5" stroke. Anyone running this stroke crank or should I stay with with a 4.25 or 4.21. Curious what your combo might be and performance numbers.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: gs462 on November 17, 2016, 09:37:07 AM
Hi, guys I'm new to Pontiacs. Can you tell me what is the best  production head to use on a 461 stroker. the heads will be fully ported but id like to start with the best flowing factory head.


Thanks.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: oldskool on November 17, 2016, 12:49:02 PM
"...tell me what is the best  production head to use on a 461 stroker..."


The best reasonably priced iron heads, for a pump gas stroker are the 6x-8 & 6x-4 heads. The 5c-4 & 5c-8 heads are nearly identical, but much less common. The 6x heads were used on '75 thru '79 models. Therefore they are quite common and still sell for a reasonable price.

The round port heads such as Ram Air IV, 455HO, & SD455 flow better, but are now VERY pricey. :(
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: oldskool on November 17, 2016, 12:54:40 PM
So a local engine builder I know has a 1971 455 engine that I am going to go have home build. Crank condition is unknown so but the time mag it and do any other work I we can buy a new forged crank. Since price does not seem to vary much between stroke lengths considering maybe going as up to 4.5" stroke. Anyone running this stroke crank or should I stay with with a 4.25 or 4.21. Curious what your combo might be and performance numbers.

If & good condition & ground correctly the 455 crank is just fine. But, if you go to an aftermarket forged crank, I'd stay with either a 4.21 or 4.25 stroke. A 4.50 stroker will have too much low end torque for a street car, with hard tires. Just a waste of power. IMO

A 4.21 stroke engine, with 6x heads, and a decent HFT cam can easily make near 400hp, at 5000rpm, & 500ft lbs of torque, down in the 3000-3500rpm range. Of course, more power is easily obtainable, with head and/or cam upgrades.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: chief poncho on November 17, 2016, 01:59:18 PM
Well when you say production, do you mean readily available or are you open to more rare and thus expensive alternatives. 

Best flowing Pontiac head ever is the RAM AIR V head, but good luck ever finding any not to mention exhaust and intake manifolds.  These also were only available over the parts counter at dealerships and were never installed on a production line car.

Best flowing cast iron head is the 73 and 74 SD455 heads, cast number 16/x, but again, you'll pay a fortune for these.  Any round port Ram Air II/IV or HO head will outflow all other D-port heads, but again are going to be very expensive and not worth the money when compared to an aftermarket aluminum head.  RAII and IV are going to have small combustion chambers and put your CR over 13:1 unless you dish the pistons.  The later '71 and '72 HO heads have large combustion chambers and will drop your CR down to around 8.5:1.  See the following link for the cast numbers http://www.wallaceracing.com/head1.htm.

Now for real options using factory cast iron heads that are readily available and affordable, I would look at the '71 and '72 400 4bbl heads cast number 96 and 7k3, followed by maybe the 6x-4.  Any of these would make a good place to start.

But in all honesty, unless you know someone that knows how to port the heads and they are doing it for free or little money, I would move right past the factory Pontiac heads and go with the Edelbrock or Butler heads.  You can get either D-port or Round Port designs.  By the time you buy a decent core, have all the machine work performed, plus replace components the aftermarket heads will more than likely outperform them right out of the box.  With porting, the aftermarket heads will far outperform pretty much any factory head.

Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: gs462 on November 17, 2016, 08:29:38 PM
I appreciate the replies, My buddy did head porting for a local race shop for 30+ years, so the port work and the valve job wont cost me anything. What do you guys think of the 670 head?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: chief poncho on November 17, 2016, 10:43:07 PM
The 670 head would be great on a 400, but even then the compression is pretty high.  With the 72cc combustion chambers it'll bump your static compression over 12.5:1 or more.  I would stay away from any pre-70 389/400/428 head or you'll have exactly the same problem.  If you can find them, and they are expensive some 1970 455HO d-port heads wouldn't be bad either, they are cast number 64, but again are more expensive than some of the other options posted.  Take a look at the link to Wallace.  It lists the engine, year, cast number, valve size, and chamber size for most heads.

Here are some other options from that list:

1970 15's 87cc but small valve press in studs.
1973 4x or 4c but be careful about combustion chamber size some 4x's were 98cc and others 114cc
1975 5c but you will have to have the studs drilled and tapped otherwise live with the pressed in stock pieces.

If you wanted to go with recessed pistons, you could probably use the 670's or other small chamber heads. 
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: gs462 on December 01, 2016, 08:58:34 PM
Chief thanks for the answers Im a complete noob when it comes to Pontiacs. Can you tell me what the max stroke my 400 block will take before I have to do major clearance work??
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: chief poncho on December 02, 2016, 05:20:38 PM
I don't know what the limitation is, but there are several aftermarket stroker kits for the 400 that'll put you at about 4.21.  I believe those kits come with cranks that are machined to fit without modifying the 400 block.  Keep in mind a factory 421-455 crank won't work in a 400 unless you have the main journals turned down to 3.00" vs the 3.25" 421-455 size. 

Looks like Butler sells kits that go up to 4.5" stroke!  I don't know if those require machining, but most likely would.

http://butlerperformance.com/c-1234863-engine-components-internal-rotating-assemblies-stroker-kits-400-blocks-406-495-cu-in.html
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: gs462 on December 04, 2016, 06:37:29 PM
I don't know what the limitation is, but there are several aftermarket stroker kits for the 400 that'll put you at about 4.21.  I believe those kits come with cranks that are machined to fit without modifying the 400 block.  Keep in mind a factory 421-455 crank won't work in a 400 unless you have the main journals turned down to 3.00" vs the 3.25" 421-455 size. 

Looks like Butler sells kits that go up to 4.5" stroke!  I don't know if those require machining, but most likely would.

http://butlerperformance.com/c-1234863-engine-components-internal-rotating-assemblies-stroker-kits-400-blocks-406-495-cu-in.html

Thanks that is what I was wondering Id like to make the most cubes I can so as to make the most power while still looking stock.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Rapp79 on August 07, 2017, 07:02:49 PM
I'm new to the forum so sorry If I've messed something up posting. Anyway, I'm in the process of swapping the transmission and 403 for a new th350 and a Pontiac 400 I'm currently having built. The previous owner had some issues with it where coolant got into the tranny fluid and the motor was pretty bad. I fixed most of the oil leaks, redid the intake manifold gaskets and fixed the brakes. I got it good enough to drive and I drove it to school my whole senior year of highschool while restoring as much of it as I could. Anyway, I was curious what all I could use off of the 403 on the 400. I'm planning on driving to college and it's about a 25 mile trip one way so I was also curious if it would be too much for the 'ol girl. The body and frame are all solid but as soon as I swap the motor I'm planning on putting in new socks and rebuilding the suspension to make it a little more smooth.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 70RAIV455 on August 07, 2017, 07:25:49 PM
I'm new to the forum so sorry If I've messed something up posting. Anyway, I'm in the process of swapping the transmission and 403 for a new th350 and a Pontiac 400 I'm currently having built. The previous owner had some issues with it where coolant got into the tranny fluid and the motor was pretty bad. I fixed most of the oil leaks, redid the intake manifold gaskets and fixed the brakes. I got it good enough to drive and I drove it to school my whole senior year of highschool while restoring as much of it as I could. Anyway, I was curious what all I could use off of the 403 on the 400. I'm planning on driving to college and it's about a 25 mile trip one way so I was also curious if it would be too much for the 'ol girl. The body and frame are all solid but as soon as I swap the motor I'm planning on putting in new socks and rebuilding the suspension to make it a little more smooth.
Just the starter motor & The Alternator.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Grand73Am on August 07, 2017, 07:57:57 PM
I agree that the starter and alternator are about all you can use from the 403. You could have used the th350 that was on the 403, since it fits the 400 too. The motor mounts on the frame are the same if you wanted to re-use them, but they don't cost much so when swapping an engine, it's usually preferable to put new ones in.
If you have a/c, the compressor is the same, but the mounting brackets are all different.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Rapp79 on August 07, 2017, 09:41:52 PM
I agree that the starter and alternator are about all you can use from the 403. You could have used the th350 that was on the 403, since it fits the 400 too. The motor mounts on the frame are the same if you wanted to re-use them, but they don't cost much so when swapping an engine, it's usually preferable to put new ones in.
If you have a/c, the compressor is the same, but the mounting brackets are all different.
Thanks! good to know. I was thinking the water pump pulley would be the same since they look fairly similar but just to be safe I'll order one specifically for a 400. I'm putting in a new transmission since the old one was pretty hashed from the previous owner completely neglecting to flush the contaminated transmission fluid when his radiator leaked into the tranny cooler. I flushed it but it was starting to have a delay going into reverse and it's slipping gears so I got another one. The frame motor mounts are actually in pretty good shape so I'll reuse them. The A/C and heat were deleted by the previous owner so I don't have to worry about those. Other than the water pump pulley I think I'm all set with parts for the swap. Thanks again!
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Calamity on March 07, 2018, 02:02:00 PM
Looking to remove my heater and A/C unit, going to be a fair weather car, and looking for pictures on routing the house from the water pump to the back of the head. Anyone got anything? Its the 400 engine.
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: Dusty Bird on November 14, 2018, 07:53:20 PM
Hello All

Been along time since my last post, sorry.

My Question:

Has anyone installed the LONG BRANCH exhaust manifolds on a 1970, 2nd Gen Firebird????

I have a 1970 and I really like the look of the LONG BRANCH Manifolds.

If you know anyone or have any picture's that would help a lot too.

Why is it that they say they won't fit???

Any Help would be GREATLY APPRECIATED.

Thanks In Advance for any help or information.

Take Care All

Dusty


Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: stitcher on April 05, 2019, 08:55:59 PM
Since the blocks seem to be the same, can a 350 block be bored and stroked to a 400 or 455 cu. in.?
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: oldskool on April 06, 2019, 09:30:11 AM
Since the blocks seem to be the same, can a 350 block be bored and stroked to a 400 or 455 cu. in.?

They can definitely be stroked using the 4" & the 4.25" stroke cranks. Cubes will range from 383 to 413, depending on bore size. Butler offers both rotating assemblies.

https://butlerperformance.com/i-24591337-butler-performance383-388ci-balanced-rotating-assembly-stroker-kit-for-350-block-4-000str.html?ref=category:1234861

https://butlerperformance.com/i-24591338-butler-performance407-413ci-balanced-rotating-assembly-stroker-kit-for-350-block-4-250str.html?ref=category:1234861

The casting number 500810 blocks have the thin main webs, like the 557 400 blocks have. So, I wouldn't build a stroker with a 500810 block. Any other good 350 block should work OK. Max safe bore will depend on core shift, internal corrosion, etc. Some Pontiac blocks can be bored .070 or more. Some won't even safely bore .060. A competent machine shop can check the cylinder walls for thickness, to determine max safe bore size.

Especially if you use heads with 2.11/1.77 valves, you'll need valve clearance chamfers, which some call "notches", at the tops of all the cylinders. This valve clearance is needed for what some called valve "unshrouding", to allow good flow. Can also allow the use of a larger cam. These chamfers can be added to any block, using a hand grinder, such as those used for head porting. Obviously, they need to be in the correct locations, and of the correct size.   
Title: Re: Pontiac 400-455 Questions and answers. Subthread
Post by: 72blackbird on May 22, 2019, 12:09:36 PM
I build so many 400s, 455s, and 461s it almost get boring- a 350p with a 4" stroke, 6.8 BBC rods would make for a nice Poncho w/ good torque too.

350Ps are plentiful, but as mentioned that small bore does require chamfers to let you use big valve heads with it.

Geno