2020-B2-2

Author Topic: Working on 79TA Need input  (Read 518 times)

chach3835

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Working on 79TA Need input
« on: April 15, 2020, 02:01:02 PM »
Guys

I have a 79 TA with 66K original miles that has been a restoration in progress for over 15 years. My dad passed away last year and it has motivated me to get this done in his memory. He was a big gearhead and my go to person for anything cars. He taught me everything I know and I wish I would have listened better but I will figure things out. What my plan is as follows:

403 old rebuild with the same 4A heads and have the heads ported new everything on the heads
going to get a rebuild kit from Northern Auto and get the Comp 268/268 adv dur .456/.456 lift. The kit has stock pistons, I know that my CR will be around 7.9 or 8 to 1. My question will this cam and porting the heads help to waken up the motor not looking for 400HP just looking to keep the same motor but waken it up more than the stock 185HP. I know about the block and the weakness but again not looking to tear the street up just looking to waken the motor up a bit. Also I was wondering should I put in shorty headers or just keep the stock maniforlds and do dual exhaust back.  Any info you  can share to help me get it closer to 300HP would be much apprecated. I would be happy to get around 280HP.

I have another project to get my 400 plus HP out of a SBC





[URL=https://s137.photobucket.com/user/chach3835/media/20200414_101002.jpg.html]






« Last Edit: April 16, 2020, 01:57:18 PM by chach3835 »
Restoring 79 TA 66k Orig miles, Wify 67 Tempest

Wallington

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Re: Working on 79TA Need input
« Reply #1 on: April 15, 2020, 09:17:38 PM »
They have decent torque but HP will not be terribly much more than stock. A rear gear change will help, as will better flowing dual exhaust. I have not seen any figures around the shorty headers, even the manufacturer avoids them which possibly says more than the figures would. I'm not sure what cam that is as the figures are incomplete. You need one that works well with low compression and helps to build it somewhat, with added time on the exhaust side as that's where the flow it down on them, not the intake, which is limited anyway by the rest of the combo. The stock exhaust manifolds are no good for any previous engine work. Either full or shortie headers, or even the cast Thornton headers that look stock but allow for more flow and a true dual exhaust. Also good for clearance and not having to work on a hot car with headers, as well as interior heat.

A 400hp SBC may still have less torque than a fairly mild 403, depends how you drive it and how much attention you think you need and if you get on with your neighbors. Plus the chev will add many more dramas in a 79 TA in regards to chasing shaker and air cleaners parts and making adaptors and swapping lines everywhere.

Others on here may have better info and results for cam swaps in stock 403.

Email this guy, tell him your current 403 specs and he will have the ideal cam setup for you, either an existing off the shelf brand or custom.
Mark Remmel  fastone01@hotmail.com
« Last Edit: April 16, 2020, 12:05:41 AM by Wallington »

Grand73Am

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Re: Working on 79TA Need input
« Reply #2 on: April 16, 2020, 08:39:50 AM »
Ben, I don't think he's thinking of using the Chevy engine in the TA. He has another project for it.

I'm using the Thornton exhaust manifolds and they look and work great. They have 2.25" outlets and true dual exhaust. Here's a link: http://thorntonmusclecars.com/product/thorntons-350-jr-exhaust-manifolds

Since you're rebuilding the engine, I would look at the ways to increase the compression ratio for more power. A common way has been to use early 70's 350 heads, like #7 and 7A, that have smaller 64 cc combustion chambers. The head bolt holes have to be opened up to 1/2" size for the 403 head bolts. Then you can get pistons with the appropriate dish to get the desired compression.

Or, the original 403 pistons have huge dishes in them. Since you'll be replacing the pistons anyway, I'd look into getting pistons with less dish, that will increase compression ratio, and you can keep your original 4A heads.
Steve F.

Grand73Am

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Re: Working on 79TA Need input
« Reply #3 on: April 16, 2020, 08:45:01 AM »
You might get some info from this 403 "sticky" in the mechanical forum:  http://transamcountry.com/community/index.php?topic=1923.0
Steve F.

chach3835

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Re: Working on 79TA Need input
« Reply #4 on: April 16, 2020, 08:46:54 AM »
What pistons would you reccommend that would work with the original 4A heads?

Yes the chevy motor is for another project.   I am keeping the original set up for the pontiac.

Thanks!
Restoring 79 TA 66k Orig miles, Wify 67 Tempest

Grand73Am

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Re: Working on 79TA Need input
« Reply #5 on: April 16, 2020, 08:56:47 AM »
I can't make any specific recommendations, since I've only read about it. Keith Black are the ones mentioned most. So, you could Google Keith Black Olds 403 pistons and see what you can find out about them. I would also talk to a machinist who has experience with Olds and see what he would recommend.
Steve F.

Wallington

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Re: Working on 79TA Need input
« Reply #6 on: April 16, 2020, 11:20:20 AM »
Aaah yes, thought you might be tempted to swap in the Chev if the power couldn't be met! Likewise, assumed engine already nearly done rather than just a kit. As Steve said the Keith Black pistons are a good way of bumping up compression and still use stock heads. Likewise, flat top pistons, or close to them but they seem to drop in and out of production and not sure who makes anything suitable these days. Naturally, the cam is chosen to tie it all together.

My fairly mild 403 with low 'stock' intake, basic 4A head porting and larger valves, KB pistons and Thornton exhaust manifolds got 381hp/481lb tq and all low down in the revs.

chach3835

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Re: Working on 79TA Need input
« Reply #7 on: April 16, 2020, 01:38:58 PM »
Wallington, do you have specific product numbers for the parts to your build. I would be happy with over 350 HP out of the motor. Thanks bro for input.
Restoring 79 TA 66k Orig miles, Wify 67 Tempest

Maxthe222

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Re: Working on 79TA Need input
« Reply #8 on: April 16, 2020, 04:47:05 PM »
If you want to swap the heads, I wouldn't put it past you, the 4A heads really don't have too much to work with, but they should at least get you 300hp with work done to them. Something to consider is Olds Rocket 350 heads, 1968-1972 heads really bump the compression up and should bolt right on. The 1972 heads had the highest cc. But for what you're describing you should be able to get it out of the 4A's.
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1979 F/A W72 WS6
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chach3835

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Re: Working on 79TA Need input
« Reply #9 on: April 16, 2020, 07:42:54 PM »
On the 68 -72 olds 350 heads what is the cast number I should be looking for. I might have a chance to go look at some this weekend.
Restoring 79 TA 66k Orig miles, Wify 67 Tempest

Grand73Am

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Re: Working on 79TA Need input
« Reply #10 on: April 16, 2020, 07:53:40 PM »
These are the ones I know. All are for Olds 350's.

1969 is #5
1970 is #6
1971 is #7
1972 is #7A. The "A" will be upper case and in a lower position next to the 7. There's a #7a in the early 80's, that has a lower case "a", but don't get that one.
Steve F.

chach3835

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Re: Working on 79TA Need input
« Reply #11 on: May 20, 2020, 08:06:16 AM »
Ok guys update on my build

My 403 block, pistons, crank  is at the machine shop getting its work done. I got 7A olds 350 heads at the machine shop as well. (What all should I have him do to the heads on a budget) The one questtion I have is what should I expect out of the set up I have with the cam I am going to use below. I also have a Performer aluminum intake for the motor.

Oh yea and 350 turbo tranny is rebuilt with shift kit and stock torque conv.  I plan on using either headers shorty or Thornton JR manofolds. What should I expect for HP out of this set up? Again not looking to be crazy HP but just to pep it up from original.

Thanks Guys. Any info you can share and hints that I might need would be welcomed.   

Comp Cam 42-229-4 High Energy

Engine Make/Size Olds 260-455

RPM Range 1500-5500

Lifter Type Hydraulic Flat Tappet

Int. Duration Advertised (Deg) 268

Exh. Duration @ .050 in. (Deg) 218

Exh. Duration Advertised (Deg) 268

Int. Duration @ .050 in. (Deg )218

UsageStreet/Performance

Lobe Separation (Deg) 110
Exhaust Valve Lift with Factory Rocker Arm Ratio (0.456
Intake Valve Lift with Factory Rocker Arm Ratio (i 0.456
Valve Lift with Factory Rocker Arm Ratio 0.456 int./0.456 exh.
Advertised Duration 268 int./268 exh.
Computer-Controlled Compatible No
Valve Springs Required Yes
Cam Style Hydraulic flat tappet
Exhaust Duration at 050 inch Lift 218
Intake Duration at 050 inch Lift 218
Duration at 050 inch Lift 218 int./218 exh.

Basic Operating RPM Range 1,500-5,500
« Last Edit: May 20, 2020, 08:13:14 AM by chach3835 »
Restoring 79 TA 66k Orig miles, Wify 67 Tempest

Grand73Am

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Re: Working on 79TA Need input
« Reply #12 on: May 20, 2020, 08:17:42 AM »
If you still have the original iron intake manifold, compare the size of the ports with the ports on the Performer intake. I think the Performer's are smaller. The iron intake may be better, other than weighing more.
Steve F.

Fbird

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Re: Working on 79TA Need input
« Reply #13 on: May 25, 2020, 06:37:19 AM »
I personally can't say much on the 403 side but i would say that the little 268 cam is like 1 step over stock smog era stuff. That was MY experience in a 400 poncho anyway.
I would recommend contacting Mondello or Rocket racing for Olds power combo's. The camshaft is the BRAIN on the engine. Far too many things to match up with to get the CORRECT outcome. Your already there....already replacing it....not reinventing the wheel (like putting in a roller)...just 1 stick vs another stick! 1 works ....another 1 works VERY GOOD.
67 Firebird
1980 Turbo TA (injected 400 now :) )

phil400

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Re: Working on 79TA Need input
« Reply #14 on: May 30, 2020, 10:01:22 AM »
That's the old comp 268H very good cam for lower compression engines at about 8~8.5 to 1, with 350 heads you have now it might give you higher compression than that cam is designed for building too much cylinder pressure.
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Re: Working on 79TA Need input
« Reply #14 on: May 30, 2020, 10:01:22 AM »


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