whats the diff with the casting #'s
 

I was just curious my heads are 241, and my new set are 8xx cant remember at the time..whats the diff? thanks

241 were on corvettes and 01-02 f-bodies 853 are 99-00 heads. both LS1 style.

What they said ^

so is there any real difference between the 2? cuz the ones i got from MTI were 853 casting while the ones on my 02 are 241

Once they're ported it doesn't matter.

If they have been ported, then i beleive it doesn't matter. But if they are stock, i think the 241's-01-02 are better heads.

according to smokemup.com nothing. http://smokemup.com/tech/ls1.php but, from what i've heard, stock vs stock, the 241 flow better. once ported, all bets are out the window.

mines a 2000 ls1 and came stock with 241 heads :confused:

must be a very late 00. because my 00 formula comes with 853 heads.

I've seen both 241 and 853 on 00 f-cars.

guess i got a lil lucky :gruffy:

also i have heard that right under ur spark plugs on some heads there is a lil triangle. if you have those then your heads are suppose to be stronger. the triangles are a bi-product of how the heads were casted...dunno though thats just something ive heard

Semi Permanent Mold (SPM) process, as opposed to sand cast heads. Basically, the SPM process turned out more uniform and smoother textured heads.