What is so special about the casting numbers on heads. Everyone always ask what is the number, why?

 

different casting numbers denote different head revisions, mold processes, port and combustion chamber shapes and sizes.

 

so which stock casting number would be the best one, for the LS1

 

It all depends on what youre looking for. 803, 853 and 241 castinsg cam stock on the ls1. Of those, the 241 is the best. The 243 came on the ls6 motors and flows a little better and has more compression. The 5.3L castings have a smaller combustion chamber for even more compression, and after installing a larger intake valve, they flow as well or better than 241's. 317 6.0L castings have the same ports as ls6 heads, but with a larger combustion chamber for lower compression.

 

Thanks that is what I needed to know

 

Good info...