Ok, I just got a hook up for a 400 sbc out of a '76 Trans Am. The guy has this TA sittin around with a new double timing chain set on it and a new cam all with a 9" rear all for free! Right now I have a '91 RS convertible with a 5 speed and the LO3.

He told me that the engine needs some new heads because the stock 400's suck. Can you guys tell me what I'm going to need to do on this car to get the engine in there and running and what kind of heads I can run on there. I don't have much money at all. I saw some LS1 heads for sale for like 350 bucks, but I dont know if those heads will bolt up to that block and also if the carb and manifold will bolt up. Sorry for the length but any advice on this would be appreciated.

 

It's unlikely it's a Chevy small block, as those never came in 2nd gen Trans Ams. Not impossible, but unlikely.

If it really is a SBC, and it has stock 400 heads, then they suck. But since we already know it didn't come in the car, who knows what might be on it.

First thing to do is to verify that it's really a Chevy motor. If it's a Pontiac 400 or a Olds 403, you don't want it; even though those can be made to run fairly strong, they are far from a direct fit into one of these cars, and for most people the grief of shoehorning them in isn't worth it. But if it's a Chevy motor, then find out what heads are on it.

Don't concern yourself about the timing chain; it's a $25 part. Big deal.

Those cars also didn't come with a 9"; if it's the stock rear, it's a 8½" 10-bolt.

 

yeah sorry I'm an idiot its a Pontiac 400 with stock heads and the rear is I think a Ford 9". The only reason I said the timing chain set is that I won't be able to do this work on my own and he said its all sealed really well now.

I thought that this engine would swap right in but from what your saying it sure doesn't sound like it. I was hoping I could get this engine to run like a beast. Would you mind expanding on your thoughts about this engine?

 

It might be an OK motor as far as it goes, but that kind was never installed in one of these cars... you have to deal with all the usual motor swap issues, like mounts, exhaust, the fact that your trans or bell housing won't bolt to it, accessories could be a real bear, etc... It's one of those deals where the "free" motor would cost you more by the time it's actually installed and working than going out and buying the right motor in the first place would.

What makes you think it's a F*rd 9"? People wouldn't give something like that away, it costs $2000 to buy it. If it's done right, he could sell it to a racer instantly for at least $1000. But regardless of all that, it won't fit your car: 2nd gen cars have leaf springs, a totally different rear suspension form your car. you'd have to deal with massive swap issues with that too.

But of course free is good, as far as that goes. On the other hand, if you can't change a timing chain for whatever reason, then this deal isn't for you.

 

Alright thanks a lot for the info. It sounds like this swap is not going to work out too well. It's not that I can't change things such as timing chains and what not but I do not have the proper tools to do any kind of work like that. I suppose I have to rethink my engine dilema, but thanks for the information and advice guys.

 

I can send you some pictures of a poncho 400 in a 3rd gen. It is a tight fit. The design of the heads make it tough. The "double angle" heads make a close fit from the exhaust manifolds to the motor mounts. The oil filter sits pretty much right on top of the subframe. It is almost impossible to fit headers in there. The other issue is hood clearance.

As I said, I can send you some pictures. I turned down a good offer on a pont. 400 after I got them. Not to mention, have you looked at the price of parts for a pontiac motor vs a sbc? Expect to pay 1.5-2X as much for the same kind of part.

 

The Pontiac 400 is a WONDERFUL engine... they made gobs of torque, and with just a little work, can be made to have the oodles of Muscle Car Horsepower that they were originally designed for.

However, IMHO, the 3rd gen ONLY ever came with a SBC V8 in it.... (as far as V8s go) and for that simple reason, it isn't cost effective to try to put a Pontiac motor in it. I know it's been done, but you'll end up spending more money than you need to.

Hey, if the motor and everything is free.. take it and sell the parts, or the whole car. With that money, you could turn around and buy yourself a decent Chevy 350, or a Crate motor.


RB83L69, they DID actually offer Chevy motors in 2nd gen Pontiac Firebirds. Believe it or not, it is the EXACT same motor as found in the 82-87 f-body. I'm talking about the 5.0 liter LG4 Carbureted V8 Small Block Chevy.

They offered the 305 LG4 in 1980 and 1981.

The LG4 was actually available in EVERY model of the 1980-1981 TransAm with the exception of the Turbo TransAm because of course that was the 4.9 301 Pontiac motor.

My 1981 TransAm actually came with the 305 small block chevy. It was actually the base motor because it actually put out less power than the 301 Pontiac Motor.

The only good thing about this, is that my 81 TransAm was originally set-up for a small block chevy..

So when I bought the "rolling chassis" of my 81 TransAm for $300, I knew JUST where to drop my "1974 350 4-bolt with Corvette HO heads" in.

 

Yes, you're right, but that was a Chevy 305, not a Chevy 400.... perhaps I should have been clearer. Thanks for the clarification.

 

RB83L69, right...

When I still had my 82 TransAm... I was looking for possible motor configurations... I wanted a 400. I knew it was the biggest V8 I could easily drop in.

EVERYONE kept telling me not to.

I still don't understand why the 400 sbc is considered such a poor motor. Is it because it's less reliable?

I don't see too many of them around, so it makes me wonder.

It seems to me though that it would be a veritable torque monster over the 350. Like night and day difference between the 305 and the 350.


By the way, I was just reading up on Pontiac motors and came across this...

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The engines initial plan was to bring back memories of the SD-421 of the early sixties, however the official title was "Ram Air IV". All Trans Am's were fitted with dual exhausts and the tail pipes had chrome extensions.

Although the horsepower rating between the two engines is awful close, this was a popular tactic in the late sixties and early seventies to under rate the engine's power. Insurers were charging heavy premiums for high horsepower cars, so this was the manufacturers loophole. Torque peaks for the R/A III and IV are 430@3400 and 445@3900 respectively.

Ram Air engines also received additional finese during assembly. Components were carefully chosen and held to higher tolerances than the other engines being put together in the engine plant. Although the engines were not "hand assembled" so to speak, the engines did recieve that something extra to bring them as close to the blueprint standards.

The Ram Air IV featured specific cylinder heads, camshaft and a power peak of 5500 rpm vs 5000 rpm.

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HUGE difference in the meaning of "RAM-AIR" back then, than it holds to today's standards.

In the T/A of today, RAM-AIR means a hood scoop!

Back then, they actually used better heads.. etc..

 

Thanks a lot for all your feedback on this guys. From what you guys are all saying it sounds like this 400 would end up costing me way too much even though it is free to begin with. Thanks a lot again you've all been a big help to my decision making.