I'm not certain this is the issue why my head gaskets only lasted ninety something thousand miles in the past, but I learned that the RA when resurfacing heads can be critical.
After doing a lot of research into head gaskets for my subaru I learned about RA. They stated that if you go to a machine shop and you see a lot of small block chevy heads all over and thats what they specialize in chances are they can't achieve the RA needed for aluminum heads especially with certain aftermarket gaskets. Granted our head gaskets are graphite.
It is very interesting because the first thing I noticed when I got the heads back was that I could see and feel machine marks on the heads. They weren't high enough to catch a nail on, but I know they weren't like that when I brought them in. I trusted the guy because he builds extremely high dollar race engines for the local dirt track champions. I guess with sbc's and iron heads you can get away with it. My new SHO heads I installed on my spare motor didn't have these machine marks that I could see or feel. Take it for what it's worth.
After doing a lot of research into head gaskets for my subaru I learned about RA. They stated that if you go to a machine shop and you see a lot of small block chevy heads all over and thats what they specialize in chances are they can't achieve the RA needed for aluminum heads especially with certain aftermarket gaskets. Granted our head gaskets are graphite.
It is very interesting because the first thing I noticed when I got the heads back was that I could see and feel machine marks on the heads. They weren't high enough to catch a nail on, but I know they weren't like that when I brought them in. I trusted the guy because he builds extremely high dollar race engines for the local dirt track champions. I guess with sbc's and iron heads you can get away with it. My new SHO heads I installed on my spare motor didn't have these machine marks that I could see or feel. Take it for what it's worth.
