[78MayanW87]

Hello all! New around here and about two months ago I bought a '78 Trans Am with a 400. She's runs...not bad...a little tired so I am wanting to do a rebuild and was hoping that you all may be able to help me out with some performance parts direction. I don't have any information on what has been done to the engine internally but it is not numbers matching and has had some modifications. Here is what I have so far: 1977 block (XA code) with 500557 casting (I have read of the pitfalls of a *557 block) #62 heads with a J288 date code Intake manifold code: 481733 which I believe is from a 1971 HEI ignition however I don't know if it is original or what if anything has been done to it. All I can tell you at this point is it is a Delco-REmy and has an internal coil. Q-Jet TH350 A/C, PB, PS
Rear end gear ratio - I haven't pulled the cover yet, but it is either 2.41 or 2.56 has headers

I am wanting to build this up to the 350-400 hp range with. From what I have read 400 hp is about the safe limit on these 557 block castings. This is just going to be an occasional driver with a little kick and looks good under the hood.

I have reached out to Butler Performance and they came back with their custom grind Comp Cam Kit: 51-423-11 which is 276/282, 224/230, .503/.510, 114 LS. They also recommend an Edelbrock Performer RPM with a drop base air cleaner, a 800 cfm Q-Jet and a set of Doug's 1-3/4 headers.

I figured I would throw this out to the Forum and get your thoughts as well. Let me know what you think and if I can provide any additional information and as this question always comes up, I do have experience in rebuilding engines, not Pontiac though, the tools, equipment and shop space to do it.

Thanks in advance for your expertise. Lee

[PunchT37]

If you don`t change gears to 3.08 to 3.23`s at least, watch the cam size. And that cam is too big. I would also keep the stock intake.

[78MayanW87]

Originally Posted by PunchT37

If you don`t change gears to 3.08 to 3.23`s at least, watch the cam size. And that cam is too big. I would also keep the stock intake.

To be clear, the intake is not "stock" it came off of a '71. When I made the post, I thought I was putting bullet points before each of the engine components that I had identified but it did appear to have taken and end up in a long stream of consciousness...my apologies

[PunchT37]

Originally Posted by 78MayanW87

To be clear, the intake is not "stock" it came off of a '71. When I made the post, I thought I was putting bullet points before each of the engine components that I had identified but it did appear to have taken and end up in a long stream of consciousness...my apologies

I was meaning stock compared to that RPM manifold. That `71 manifold and 62 heads are good to go for your HP goals.

[tom s]

For a street car I would not do headers.The Ram Air manifolds would be a better choice,I would not be afraid of the cam with 114LC.The factory manifold with a good OJ is hard to beat.Pretty sure Sean at SMI does Butler QJs which is a plus.Tom

[77 TRASHCAN]

X2 on the Ram Air manifolds, BUT check availability of them first, if that becomes your plan. Availability of some of the RA exh manifolds has not been great. I've read too much about this issue, here, in the last 2 years.

Use the 71 intake, it is excellent!!! That cam from Butler sounds excellent to me (I'm not an expert...) The Quadrajet is the only way to go!!! Might post carb number, if its the 78 carb, they are some of THE best.

A gear change to 3.08 or 3.23 would make it more awesome!!!

Looking forward to your build experience...

[78MayanW87]

Originally Posted by 77 TRASHCAN

X2 on the Ram Air manifolds, BUT check availability of them first, if that becomes your plan. Availability of some of the RA exh manifolds has not been great. I've read too much about this issue, here, in the last 2 years.

Use the 71 intake, it is excellent!!! That cam from Butler sounds excellent to me (I'm not an expert...) The Quadrajet is the only way to go!!! Might post carb number, if its the 78 carb, they are some of THE best.

A gear change to 3.08 or 3.23 would make it more awesome!!!

Looking forward to your build experience...

Many thanks!! Below is a pic and description that I pulled off of Ames. Is this what I should be looking for or something else?

[tom s]

Yes it is,be sure you get the Dport version

[78w72]

x3 on using the stock intake over an RPM which require a drop base... of course butler will suggest that intake so they can sell you a drop base air cleaner. the factory air cleaner & a stock intake will perform as good or better than the rpm & drop base at your power level. gasket matching the intake & even consider porting it like cliff ruggles intake mod.

if the cam is one of the XE models im sure there are better options, cliff r or others can make a better suggestion on cams for your combo of parts.

dont need to pull the rear cover to confirm gear ratio, there is a 2 letter code stamped on the pass side axle tube that will tell you the gears, if they are original.

[78MayanW87]

Originally Posted by 77 TRASHCAN

X2 on the Ram Air manifolds, BUT check availability of them first, if that becomes your plan. Availability of some of the RA exh manifolds has not been great. I've read too much about this issue, here, in the last 2 years.

Use the 71 intake, it is excellent!!! That cam from Butler sounds excellent to me (I'm not an expert...) The Quadrajet is the only way to go!!! Might post carb number, if its the 78 carb, they are some of THE best.

A gear change to 3.08 or 3.23 would make it more awesome!!!

Looking forward to your build experience...

Looks like I have a 17058274, which if I am decoding correctly is from a '78 Pontiac with automatic transmission.

Regarding the RAIII exhaust manifolds, I have checked some of the usual suspects and it appears to be late this year or early 2023 before any more are being reproduced.

[78MayanW87]

Originally Posted by 78w72

x3 on using the stock intake over an RPM which require a drop base... of course butler will suggest that intake so they can sell you a drop base air cleaner. the factory air cleaner & a stock intake will perform as good or better than the rpm & drop base at your power level. gasket matching the intake & even consider porting it like cliff ruggles intake mod.

if the cam is one of the XE models im sure there are better options, cliff r or others can make a better suggestion on cams for your combo of parts.

dont need to pull the rear cover to confirm gear ratio, there is a 2 letter code stamped on the pass side axle tube that will tell you the gears, if they are original.

How would you suggest I get Cliff to weigh in on the build?

[77 TRASHCAN]

I didn't think THAT cam would be one of the XE's, having a 114 LSA....

A second yes on that picture of the exh manifolds!, BUT as I mentioned, make sure they are available. There's a buncha folks that sell parts, that list or show a part, then yank the rug out from under you when ordering...plus giving you a short availability time, thn that time rolls into months and beyond.
If I were you, and found the manifolds in stock some where, I'd get them on the way to your house, ASAP. THose products have painfully difficult to obtain, in last 2 years...

[25stevem]

If you have under 2.73 gears in that 8.5” rear in your TA your going to have to also replace the guts / differential to get into 3.08 or higher gears , also if you do not have a posi rear now is the time to do that!

You can make a solid 350 hp thru the stock log type exh manifolds if there not rusted and scaly on the inside and if they blow out thru mandrel bent head pipes so don’t fret.
Down the road you can swap over when the parts come back in stock.

[65madgoat]

Regardless of what engine direction you go, I feel adding a Holley or FiTech EFI, and a Tremec TKX manual O/D transmission swap, will by far give you the most fun ;-)

[jhein]

So what you're looking for is like a RAIII type output. My vote for that power level is to keep the stock intake and Qjet. Keep the heads. Get pistons to get the CR to 9.5. Butler cam recommendation is probably good. No headers. If you can't find RA exhaust manifolds, for now just run what you have until you can get them.

Then, if your budget permits, the TKX with a 3.55 or 3.73 rear. That will make a huge difference. Or, if you don't want to swap the tranny, a gear vendors is another option.

I think the drive line changes would do nearly as much for you as the motor, and doing both would be totally awesome.

[78w72]

Originally Posted by 78MayanW87

How would you suggest I get Cliff to weigh in on the build?

he may see this & reply with some cam & other suggestions. or you can send him PM.

others on here can suggest a cam or confirm if the butler one is good for your combo.

& no reason to be afraid of headers, if the ram air manifolds arent available i would rather have headers than stock exhaust manifolds. no need for super expensive dougs, hedman makes an excellent header that fits great on 2nd gen firebirds will work for a manual trans too. hedman #28150 are the best bang for the buck for these cars... but availability may be an issue like many other parts right now. jegs shows ship date of 6/7. i have a set on a 78 t/a that were pretty simple to install & have been leak free for 12 years now using the stock supplied fiber gaskets.

[78MayanW87]

Originally Posted by jhein

So what you're looking for is like a RAIII type output. My vote for that power level is to keep the stock intake and Qjet. Keep the heads. Get pistons to get the CR to 9.5. Butler cam recommendation is probably good. No headers. If you can't find RA exhaust manifolds, for now just run what you have until you can get them.

Then, if your budget permits, the TKX with a 3.55 or 3.73 rear. That will make a huge difference. Or, if you don't want to swap the tranny, a gear vendors is another option.

I think the drive line changes would do nearly as much for you as the motor, and doing both would be totally awesome.

Many thanks!! First, I want to say thanks to everyone that has weighed in! Honestly I really expected to get 15 different responses from 10 different people, but for the most part there is a general consensus around keeping the QJ, ‘71 intake and heads and most don’t have an issue with the Butler/Comp cam recommendation Pretty much across the board, everyone is for RAIII exhaust. As you have also recommended, most agree that I need lower rear ended gears and I wasn’t even considering a TKX auto/manual swap, but I sure am now!! For clarification on my current exhaust, I am running 1-3/4 headers of unknown origin. I think I will likely get in line for some RAIII exhaust but use my existing headers if they aren’t in by the time I get ready to reinstall the engine and just swap them out whenever they arrive.

Thanks so much to everyone and I am by no means shutting down the thread, just wanted express my gratitude to the Forum.

Keep the advice coming!!! I really need all I can get!!

[78MayanW87]

Originally Posted by 78w72

he may see this & reply with some cam & other suggestions. or you can send him PM.

others on here can suggest a cam or confirm if the butler one is good for your combo.

& no reason to be afraid of headers, if the ram air manifolds arent available i would rather have headers than stock exhaust manifolds. no need for super expensive dougs, hedman makes an excellent header that fits great on 2nd gen firebirds will work for a manual trans too. hedman #28150 are the best bang for the buck for these cars... but availability may be an issue like many other parts right now. jegs shows ship date of 6/7. i have a set on a 78 t/a that were pretty simple to install & have been leak free for 12 years now using the stock supplied fiber gaskets.

I sent Cliff a PM and he got back to me already. I actually have a set of 1-3/4” headers on it now. I think I’ll order some RAIII manifolds and stick with what I have until they arrive. Whenever that is... BTW when I spoke to Ames today about those RAIII manifolds they said that they are having their own made. But having to get in line at the foundry behind the big boys like John Deere have really pushed things back.

[jhein]

When I posted I kinda forgot that you said you have headers. If you already have them, and apparently they fit well, then I agree, no need to change them unless your going for a stock look or something.

[PunchT37]

Originally Posted by jhein

When I posted I kinda forgot that you said you have headers. If you already have them, and apparently they fit well, then I agree, no need to change them unless your going for a stock look or something.

I agree. If they don`t leak, keep em. They`ll help that big cam out. No need for new head pipes. 350 to 400 hp on a 557 block doesn`t need a lot of thought or money.