Which Pontiac heads for more compression?

[JimRochester]

I did a search but didn't find anything so I'm starting a new thread.

I have a 1978 Trans Am with the Pontiac 400 and an automatic. In my younger days I built the crap out of a 428 and flew down the track in a similiar 78. I don't want to do that anymore but I would like to perk up the 400 just a bit. Basically make it what it should have been. Bring it up to the early 70's standards of a 400. I read that I could use heads coded 96 or 7k3 and that will boost compression from the paltry 7.6:1 to around 9:1.

Is this information correct?
Any other heads I could use to achieve the same result?
Any suggestions on a cam? It's not a show car but I want to stick with good idle quality. It has those horrible 2.56 gears which I'm sure I'll change at some point but I want to get my power in the low end.

Thanksopcorn:

[Morley]

Ram Air IV heads and look into Isky cams.

[Whoaru99]

Originally Posted by JimRochester

I did a search but didn't find anything so I'm starting a new thread.

I have a 1978 Trans Am with the Pontiac 400 and an automatic. In my younger days I built the crap out of a 428 and flew down the track in a similiar 78. I don't want to do that anymore but I would like to perk up the 400 just a bit. Basically make it what it should have been. Bring it up to the early 70's standards of a 400. I read that I could use heads coded 96 or 7k3 and that will boost compression from the paltry 7.6:1 to around 9:1.

Is this information correct?
Any other heads I could use to achieve the same result?
Any suggestions on a cam? It's not a show car but I want to stick with good idle quality. It has those horrible 2.56 gears which I'm sure I'll change at some point but I want to get my power in the low end.

Thanksopcorn:

IMO, not much sense doing any perf mods until you get rid of those 2.56 cogs. With the 400 you have plenty of potential for torque, but the rear gears are already holding back the acceleration.

Is yours a "true" Pontiac 400, or the Olds 403 engine?

I think it was the heads from the Pontiac 350 that boosted the compression on the Pontiac 400.

[JimRochester]

Mine is a true Pontiac 400. I have the build sheet and confirmed it with the VIN.

I agree, those 2.56 gears are going to hold it back. Back 20 years ago I built a 428 and had 4.10's but I raced that one in the 1/4. Eventually I'm sure I'd find 3.23 or 3.42's which will give it a bit more spunk. It's just that it is an original survivor so I want to keep it from falling apart. Plus I'm not looking for a screamer. I just want to punch it up a little bit to get it more into the high 200's or low 300's HP like the early 70's 400's.

[88camaroproject]

i got a 400 and i have heads from a crate 350 on it, they have 64cc combustion chambers and the block is bored 30 over....... trw pistons and like 12 to 1 compression. mines a sbc and any sbc heads will bolt on but you have to drill the steam holes in them. but i am not sure about the pontiac engines. it shouldnt be to hard to make some nice power with that thing. but you most effective mod will have to be doing those gears out back. ass much as you dont want to hear that it would be the cheapest way to wake the car up.