Author Topic: Pontiac 400-455 Questions and answers. Subthread  (Read 151141 times)

TransAm_Stan

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76 400 (re)build
« Reply #160 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
76 White exterior, Blue interior "Toastee"
LS3, TKO600, Hydroboost
Hydraulic clutch
Western Hurricane rims

76 White 400 4sp. blue/white interior (project)
Can't get any more apart than I have it!

critter

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #161 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.
Been there, done that, t-shirt is now a shop rag.

78TransAm

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #162 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?
Mark Haynes
TAC Moderator
Warner Robins, Georgia

1974transam.blogspot.com/

www.MarkHaynesArt.com




1974 455 Trans Am
1978 400 Trans Am

critter

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #163 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.
Been there, done that, t-shirt is now a shop rag.

78TransAm

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #164 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.
« Last Edit: March 04, 2012, 06:51:36 PM by 78TransAm »
Mark Haynes
TAC Moderator
Warner Robins, Georgia

1974transam.blogspot.com/

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1974 455 Trans Am
1978 400 Trans Am

Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #164 on: March 04, 2012, 06:29:39 PM »

falcon4

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #165 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?
Jon

1966 Chrysler Valiant Regal 225
1976 Pontiac Trans Am Firebird 455
1979 Pontiac Trans Am Firebird 403 (my newest lawn ornament)
1979 Pontiac Firebird 301 Base Model......
1977 Ford F-100 4WD 351
1979 Camaro Z28 350 (wouldn't work in an iron lung)
2004 Ford XR-8 Falcon 5.4
1972 Lemans Station Wagon 455 with Endura nose option.

Perth, Western Australia

LeighP

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #166 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.
Regards,
Leigh

Sydney, Australia
1969 Pontiac Firebird 400 coupe (project)

Former Firebirds -
1971 Pontiac Firebird 455
1977 Pontiac Trans Am
1976 Pontiac Trans Am
1967 Pontiac Firebird 400 convertible
1967 Pontiac Firebird 400 coupe


falcon4

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #167 on: March 07, 2012, 06:56:04 PM »
Yes Leigh, Please post dimensions.  I'll only be running headers of cause... 8-) 8-)
Jon

1966 Chrysler Valiant Regal 225
1976 Pontiac Trans Am Firebird 455
1979 Pontiac Trans Am Firebird 403 (my newest lawn ornament)
1979 Pontiac Firebird 301 Base Model......
1977 Ford F-100 4WD 351
1979 Camaro Z28 350 (wouldn't work in an iron lung)
2004 Ford XR-8 Falcon 5.4
1972 Lemans Station Wagon 455 with Endura nose option.

Perth, Western Australia

LeighP

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #168 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!
Regards,
Leigh

Sydney, Australia
1969 Pontiac Firebird 400 coupe (project)

Former Firebirds -
1971 Pontiac Firebird 455
1977 Pontiac Trans Am
1976 Pontiac Trans Am
1967 Pontiac Firebird 400 convertible
1967 Pontiac Firebird 400 coupe


Blondylab

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Which Cam for my 1978 W72
« Reply #169 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

GM4LIFE

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #170 on: September 11, 2012, 02:11:16 PM »
Which Trans Am is faster stock, 1976 455 4spd or 1979 400 4spd?

TripleTransAm

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #171 on: September 11, 2012, 04:01:45 PM »
uh oh...
/Steve
1987 Trans Am GTA
1998 Trans Am WS6
1978 Trans Am L78 (sold)
1978 Trans Am W72 4-speed WS6

Ben

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #172 on: September 11, 2012, 08:04:48 PM »
Depends on the driver!
Trans Am-less at the moment...

Home of the Mess

cpgta

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #173 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?

LeighP

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #174 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.
Regards,
Leigh

Sydney, Australia
1969 Pontiac Firebird 400 coupe (project)

Former Firebirds -
1971 Pontiac Firebird 455
1977 Pontiac Trans Am
1976 Pontiac Trans Am
1967 Pontiac Firebird 400 convertible
1967 Pontiac Firebird 400 coupe


Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #174 on: September 19, 2012, 04:19:33 AM »



cpgta

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #175 on: September 19, 2012, 04:56:01 AM »
thank you for the info..

zippy

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #176 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.

LeighP

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #177 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.



I then had the old mount holes plated over.



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.
Regards,
Leigh

Sydney, Australia
1969 Pontiac Firebird 400 coupe (project)

Former Firebirds -
1971 Pontiac Firebird 455
1977 Pontiac Trans Am
1976 Pontiac Trans Am
1967 Pontiac Firebird 400 convertible
1967 Pontiac Firebird 400 coupe


zippy

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #178 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?

LeighP

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #179 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:
Regards,
Leigh

Sydney, Australia
1969 Pontiac Firebird 400 coupe (project)

Former Firebirds -
1971 Pontiac Firebird 455
1977 Pontiac Trans Am
1976 Pontiac Trans Am
1967 Pontiac Firebird 400 convertible
1967 Pontiac Firebird 400 coupe


zippy

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #180 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

BlueTTA

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #181 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
You can get much farther with a kind word and a gun than you can with a kind word alone. - Al Capone

Chris
1979 Solar Gold T-top 403

Grand73Am

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #182 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.
Steve F.

BlueTTA

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #183 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.
You can get much farther with a kind word and a gun than you can with a kind word alone. - Al Capone

Chris
1979 Solar Gold T-top 403

johnnys81t/a

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #184 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?

chief poncho

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #185 on: December 10, 2012, 01:39:58 PM »
If its completely stock with 6h heads its factory rated to around 7.6:1. 
1971 Lucerne Blue Trans Am (455HO, Automatic) - currently my project car.
Previously Owned TA's/Musclecars: 2002 Pewter WS6/M6 Trans Am, 1968 Dodge Superbee 383/4speed,  1975 TA 455/4speed, 1989 Mustang LX 5.0/5speed, 1980 TA Indy Pace Car, 1977 TA 400/Auto, 1989 GTA 350TPI, 1990 GTA 350TPI, 1986 IROC 305TPI, 1989 Mustang LX 5.0/Auto, 1993 Mitsu 3000GT VR4 (and probably a few I've forgotten about)

NCBadBird1979

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #186 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?
1979 Trans Am Black & Gold Hardtop

Ben

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #187 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.
Trans Am-less at the moment...

Home of the Mess

krhsierra

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #188 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.

1blk1

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #189 on: August 24, 2013, 12:15:04 AM »
can be done but sure not easy
"the more im around people, the more i like my dogs"

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krhsierra

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #190 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

Clint S

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #191 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.     
72 Firebird Esprit 455
Get high on milk, my cow's on grass.
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Grand73Am

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #192 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.

Steve F.

1blk1

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #193 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
"the more im around people, the more i like my dogs"

“Extinction is the rule. Survival is the exception.” Carl Sagan

krhsierra

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #194 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.

LeighP

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #195 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.
Regards,
Leigh

Sydney, Australia
1969 Pontiac Firebird 400 coupe (project)

Former Firebirds -
1971 Pontiac Firebird 455
1977 Pontiac Trans Am
1976 Pontiac Trans Am
1967 Pontiac Firebird 400 convertible
1967 Pontiac Firebird 400 coupe


krhsierra

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #196 on: August 25, 2013, 04:48:16 PM »
Ok! Thanks for the input! By the way, Leigh, your 455 is beautiful!

LeighP

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #197 on: August 26, 2013, 12:56:53 AM »
 :grin: thanks.
Regards,
Leigh

Sydney, Australia
1969 Pontiac Firebird 400 coupe (project)

Former Firebirds -
1971 Pontiac Firebird 455
1977 Pontiac Trans Am
1976 Pontiac Trans Am
1967 Pontiac Firebird 400 convertible
1967 Pontiac Firebird 400 coupe


casey1

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #198 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 .

Smokedbird

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #199 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

Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #199 on: August 31, 2015, 07:11:33 AM »
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