SBC head ID?
1) The first photo is the casting date: G241 (July 24, 1971) or C241 (March 24, 1971)
2) The cylinder head cast number appears (to me) to be 3986388 which would be a low performance cylinder head made for 307/350 engines from 1968 through 1979. Intakes were 1.72" and exhausts were 1.5".
If the cylinder head casting number is different, please post the correct number and I'll research it again.
The revise casting date doesn't make sense. The first letter designates the month, the next two digits designate the day of the month, and the last single digit indicates the last digit of the year. I've re-looked at the original photo shot, and I don't see a final "7" on the casting date so my original interpretation of March 24, 1971 still stands.
Hope this helps.





