compression

[henryw]

i have some smog heads on my 318 , cylinder pressure is 100, i have access to some 67-68 heads that arent smoggers, what will i gain ? bottom end is new with flat top pistons.

 

[Petzschler]

if you have the "302" smogger (not) heads you'll lose cr by swapping to the early heads. otherwise you'll gain pratically nothing.
why only 100psi? u put a aftermarket cam in that thing? even a 7.5:1 360 with 200k on it will make at least 120psi.

 

[henryw]

yes aftermarket cam , so cam could be the problem?.. these heads are 74-86 cast # is 4027593.

 

[moper]

I think the 68-70 318 open chamber heads are still very small. like 60ccs or something. I dont have the casting books to say exactly tho... anybody have one handy?

 

[63dartman]

those are 1.78 intake and 1.5 exhaust open chamber heads typical of the low compression 318 I'm not sure on the cc but I would guess it to be 70+.