| FAQ |
| Members List |
| Social Groups |
| Calendar |
| Search |
| Today's Posts |
|
#1
11-19-2025, 07:51 PM
|
|||
|
|||
Mismatched Heads on a 1972 YX engine
I'm looking at buying a complete running '72 Catalina engine for my GTO project, and noticed it has a 6X-4 on the driver side and a 6X-8 on the passenger side.
From what I read on the Butler site, the 6X-4 has a ~93cc chamber and the 6X-8 has a 100cc chamber. No idea if the heads have been milled down or what, but I'll likely want to replace one of them to match. I assume the 6X-4 would be more ideal on a stock YX 400 engine, to bump the compression up a bit. Or is there a better head to look for? I'll be installing my Tri-Power intake on it, and probably install a roller cam. It ran smooth and quiet, and would easily boil the tires (Posi), so hoping the bottom end is good. Pontiac stuff is quite scarce around here! Cheers, Brian
__________________
1965 GTO Coupe project in the works. PHS documented Mayfair Maize, Tri-Power, 4 Speed, 3.55 Posi |
|
|
The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.
Threaded Mode