I found a set of 5C heads which, according to the specs I have, are the same cc and valve sizes as 6X. Are there internal differences, i.e. port shape/size? Are 5C heads a good choice for a street performance 462?
I found a set of 5C heads which, according to the specs I have, are the same cc and valve sizes as 6X. Are there internal differences, i.e. port shape/size? Are 5C heads a good choice for a street performance 462?
Double A
01-30-2000, 03:59 PM
According to Pontiac Enthusiast Magazine (9/99), 5C heads are an AIR version of similar post-'72 6X's. I have always been told that the 6X's were the way to go on 455 blocks for pump gas performance. Apparently they breathe better than 5C's. If those 6X's are #8 stamped, or even if they're #4's, I'd go with them.
400 5C heads are stamped #7, 350 heads #9. If by chance you have 6X stamped #2, WOW!
Hope this helps, Double