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Discussion Starter · #1 ·
Hi, im in the progress of buying a 1979 Trans AM and have researched a lot on how to improve performance from the measly 185hp it put out. I've been told to put early heads (68-72) on it mainly 1972 #7a heads from a 350 were the best but i really cant find any anywhere i was wondering if there was there any possible way to get good performance (350-400hp) out of the #4a heads that came stock with the 403.

Thanks For any input,

Trey
 

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Old(s) Fart
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Hi, im in the progress of buying a 1979 Trans AM and have researched a lot on how to improve performance from the measly 185hp it put out. I've been told to put early heads (68-72) on it mainly 1972 #7a heads from a 350 were the best but i really cant find any anywhere i was wondering if there was there any possible way to get good performance (350-400hp) out of the #4a heads that came stock with the 403.

Thanks For any input,

Trey
The whole reason for swapping heads is to get the smaller chambers and raise the compression. The 4A heads have something like 80 cc chambers, same as a BBO. The earlier heads have 60-64 CC chambers. The problem is that the early heads also have smaller valves than your 4A heads, so you need to have them cut for the larger BBO-sized valves (Olds did this for the W-31 motors). I'm not sure where you are looking, but #4, 5, 6, 7, and 7a (not to be confused with the 7A heads on the 307s) are pretty easy to find. Cores should run in the $100/pair range.

As far as your 4A heads, the only thing you can do to increase CR is to change to flattop pistons, not an inexpensive solution. If you're looking for the best performance upgrade to a 403, get BBO heads (Cs are good, but all except Js are comparable), flattops, and a Performer RPM ported to match. The C heads worked great on a BBO 400, they'll work equally well on an SBO 403.
 

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Discussion Starter · #3 ·
looks like I should go with the 1972 350 7a heads then since it seems to be the cheapest option. Were those heads only on the 1972 cutlass? and do you think a junkyard might have them. If i do use them then i wouldn't have to change the pistons?
 

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Old(s) Fart
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looks like I should go with the 1972 350 7a heads then since it seems to be the cheapest option. Were those heads only on the 1972 cutlass? and do you think a junkyard might have them. If i do use them then i wouldn't have to change the pistons?
#4 was 1967
#5 was 68-69
#6 was 70
#7 was 71
#7a was 72

The same heads were used on all SBOs (A-body and full size) in a given year, and except for the W-31s all had the same valve sizes. The 7 and 7a heads have hardened seats, but these are simply induction hardening of the parent cast iron, not separate press in seats. If you cut the seats for big valves (or even have too many valve jobs done) the hardened area is machined away. If you do elect to have hardened seats installed, be sure the machine shop uses Olds-specific seats. The common Chevy seats are too tall and the shop will hit water if they cut the heads too deep.
 

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Discussion Starter · #5 ·
Thanks man that's some great information I didnt know the hardened valve seats could be machined away also didnt know you could install them either. so any of those heads should bump it up to about a 9.5 with the right gasket and spacing?
 

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Sure you couldnt get an LT1 or LT4 for the same money. Even a good first gen sbc. The olds motor is junk and will never make big power, just suck up cash and never make you happy. A chevy motor would be very cheap and make more power than the olds for alot less money probably enough to offset the price of the swap and chevy style trans.

Any pontiac engine will bolt in without changing the trans but if it needs to be built chevy may still come in cheaper.
LMAO!

Obviously this guy doesn't know **** from shinola when it comes to engines. the 403 Olds or even a 350 Olds can make more than enough power to make your car a blast to drive.
 

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Discussion Starter · #7 ·
LMAO!

Obviously this guy doesn't know **** from shinola when it comes to engines. the 403 Olds or even a 350 Olds can make more than enough power to make your car a blast to drive.

I know ive read enough on the 403 to know that it can be a kick ***** motor and that the windowed main webs shouldnt scare me
 

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WFO
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The olds motor is junk and will never make big power, just suck up cash and never make you happy. A chevy motor would be very cheap and make more power than the olds for alot less money probably enough to offset the price of the swap and chevy style trans.

Any pontiac engine will bolt in without changing the trans but if it needs to be built chevy may still come in cheaper.
The MAIN thing "wrong" w/Olds power is dumbasses who:

1. do not know jack about them (same thing w/Q-jet carbs), and...
2. people who try to build them like a Chevy (same thing w/Pontiac engines).

An Olds engine can perform just fine. Even the 403- as long as the expectations are realistic. They'll run w/most anything w/a ~5500 rpm redline.

But the LAST thing the hotrodding world needs is another Pontiac w/a Chevy engine in it- even if the factory wimped out and did it, too (and a 305 at that:evil:).
 

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Discussion Starter · #9 ·
The MAIN thing "wrong" w/Olds power is dumbasses who:

1. do not know jack about them (same thing w/Q-jet carbs), and...
2. people who try to build them like a Chevy (same thing w/Pontiac engines).

An Olds engine can perform just fine. Even the 403- as long as the expectations are realistic. They'll run w/most anything w/a ~5500 rpm redline.

But the LAST thing the hotrodding world needs is another Pontiac w/a Chevy engine in it- even if the factory wimped out and did it, too (and a 305 at that:evil:).
Amen to that
 

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The MAIN thing "wrong" w/Olds power is dumbasses who:

1. do not know jack about them (same thing w/Q-jet carbs), and...
2. people who try to build them like a Chevy (same thing w/Pontiac engines).

An Olds engine can perform just fine. Even the 403- as long as the expectations are realistic. They'll run w/most anything w/a ~5500 rpm redline.

But the LAST thing the hotrodding world needs is another Pontiac w/a Chevy engine in it- even if the factory wimped out and did it, too (and a 305 at that:evil:).
You can build an Olds just like any other engine, chevy, chrysler, ford, fiat, etc it DOES NOT MATTER what brand it is. Its just a big ol chuck of iron.

Get some 7a heads, add the larger valves, and port them out (these heads can flow a LOT for stock small block heads when done right), get in the 9.5:1-10:1 compression range, a good set of headers, a cam close to this one Street Strip Solid Cam - Oldsmobile V8 276/284 - Lunati Power , an RPM intake, a 800cfm or larger carb, and if you can freshen up the short block and add new bolts and a good balance job.

An easy 450+hp combo.
 

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WFO
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You are just too wrong in too many areas for me to waste my time on- I'd be here all day.

1979 TA- PLEASE use your best judgement. Listen to people who have actually done these things and not just read a mag or googled it.

Member joe_padavano knows as much about the Olds as anyone on this board, I would recommend you listen to him (I have only built two Olds engines from the ground up, a 350 and a 455).
 

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www.generationhighoutput. com
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AFA making power from stock, the 403 olds is no different from building a 400 sbc, except that it has windowed mains and so you need to keep the rpms below 6k if you have plans to abuse it. It has a huge bore and with the right heads (the bbo heads will put you ahead of the sbo in everything except static compression) it will make great power. He's not building an all out dragster and with careful consideration to how much he spends on his top end he could easily build an engine that will outpower anything chevy that displaces 5.7L (gen or gen II) at a similar cost. It's not hard, just takes careful thought and patience.
 

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The 403 olds is no different from building a 400 sbc, except that it has windowed mains and so you need to keep the rpms below 6k if you have plans to abuse it. It has a huge bore and with the right heads (the bbo heads will put you ahead of the sbo in everything except static compression) it will make great power. He's not building an all out dragster and with careful consideration to how much he spends on his top end he could easily build an engine that will outpower anything chevy that displaces 5.7L (gen or gen II) at a similar cost. It's not hard, just takes careful thought and patience.
since he's keeping RPM low a SBO head can be made to perform better than a BBO IMO. Not saying either won't work but as we both know under 500hp a SBO head is quite capable.

If prepped right either can make great power though.

Better than LT4 head- well that's another debate.
 

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Old(s) Fart
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Sure you couldnt get an LT1 or LT4 for the same money. Even a good first gen sbc. The olds motor is junk and will never make big power, just suck up cash and never make you happy. A chevy motor would be very cheap and make more power than the olds for alot less money probably enough to offset the price of the swap and chevy style trans.

Any pontiac engine will bolt in without changing the trans but if it needs to be built chevy may still come in cheaper.
Here we go. SOMEBODY had post about how the almighty SBC is the ONLY solution to any problem... :rolleyes:

I do agree, even as an Olds guy, that a Pontiac 455 in a Pontiac just feels better.

And you're right. Olds motors are worthless crap. Please send them all to me so I can rid the world of this menace... :D
 

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Discussion Starter · #15 ·
Thanks for all the input guys i went ahead and went with the 455 SD that my uncle let me have it came out of a 1973 T/A. do you guys know if it will fit right in without too many modifications and if the transmission will line up? the tranny is a th350
 

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Discussion Starter · #16 ·
Trans will bolt up but usally use the turbo 400 for the 455. You may need to swap the flex plate. But the 350 will work it may not last well if the sd is in good runnign condition. It can make a ton of power.
yea i heard the engine was really good one of the last great muscle car engines (i read that off a magazine somewhere lol). did the 400 come on the 73 TA? if so i can just pull it off of one of the 73s he has and also was the th400s available in auto?
 
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