Differences in LS1 cylinder heads? - F-Body Road Racing and Autocross Forums

I have a pair of LS1 cylinder heads (long story on how I got them). They're different castings, and I was wondering if anybody had any insight on their differences, if any. One I'm pretty sure is from an '01 Z28, the other one I'm not sure of (and can't remember which one is which).

On one of them, it reads "1256" on the inside where you usually find casting #s but then it also reads "4241" a few inches over.

The only marking I could find on the other one is "I227."

I was just looking to sell them but I don't want to sell them together if they can't be used together. I know with the thirdgens and other GM V8's there are all kinds of different casting #s and there are some physical/performance differences but have no clue on LS1 heads.

TIA.

Pat

patred View Member Profile	Mar 12 2006, 08:06 PM Post #1
Zero brand loyalty Group: Advanced Members Posts: 645 Joined: 22-January 04 From: Merryland Member No.: 145	I have a pair of LS1 cylinder heads (long story on how I got them). They're different castings, and I was wondering if anybody had any insight on their differences, if any. One I'm pretty sure is from an '01 Z28, the other one I'm not sure of (and can't remember which one is which). On one of them, it reads "1256" on the inside where you usually find casting #s but then it also reads "4241" a few inches over. The only marking I could find on the other one is "I227." I was just looking to sell them but I don't want to sell them together if they can't be used together. I know with the thirdgens and other GM V8's there are all kinds of different casting #s and there are some physical/performance differences but have no clue on LS1 heads. TIA. Pat