I'm buying a new set of dart 180cc iron eagle heads.I'm wondering what combustion chamber size I should get.64cc or 72cc.This is for a stock 350 crate motor.What is the advantage of a larger or smaller combustion chamber?Thanks bm
Its going in a 1967 nova.Stock 1994 gm goodwrench 350 crate motor.350 turbo Auto trans,3.23 rearend(i think..I cant find the casting number).weiand stealth intake,edelbrock performer 600cfm carb.Hei ignition..soon to be msd.Thats all the info I have on this motor.any opinions or advice would be greatly appreciated.thanks bm
I'd go with the 64cc heads which would allow flexibility in you choosing the compression ratio. Your crate motor may have dished pistons which would end up giving you a low compression ratio with the 72cc heads. With the 64cc heads you can always use thicker headgaskets or have the chambers cleaned up and polished to drop the C/R.
Assuming you have flat top pistons, a 64cc chamber will put you almost right at 10:1. That should work fine. It is important to know how far your pistons are in the hole so you can get the correct quench. You want it to be between .040 and .050. This will allow your fuel to mix better which will make your car less prone to detonation and make slighlty better power. If you are at all worried about the motor not being able to run on pump gas at 10:1, or you want to be able to run 87 octane, I would consider the 72cc heads since the slight power loss would not be a big deal because the car is not going to be raced . If you are at 10:1 with the 64cc head, a 72cc head will take you down to roughly 9.2:1. As stated before, knowing if you have flat top or dished pistons would help this choice out alot. In the case that you have dished pistons, the 64 is the best way to go.