Cylinder head question.

[Doug Guilds]

Does anyone have any info on the difference on the heads from a 89 3.1 vs a 91 3.1? A number in near the valve springs of the 89 heads is a 24, in the 91 heads it's a 35. I can visually see a difference in the combustion chambers but haven't CCed either yet. I'm not sure if the numbers cast into the outside of the head near the exhaust are whats used in determining what head is what, so any info on castings would be greatly appreciated.

[SappySE107]

I have read and seen pictures comparing TGP heads to other heads, but that would 88-90 vs 91+. It was as if there were more machining done to the 91+ heads in the combustion chamber but I don't know the significance of this. Been a while since I looked at the pictures and all I have are the newer gen 2 heads here, not 88-90. Casting numbers on the exhaust side are what you should look up for comparison.

[Doug Guilds]

Awesome, thanks for the info. If I can get a couple pics of the chambers I'll post em for reference purposes. I think I'm going to CC the 2 sets tonight and I'll post what I come up with just for fun.