what head gasket to run

GNcincy87

Member
the motor is bored .060 over. rjc's bulletproof head gasket says its designed to run with a bore of 3.830 or smaller. im guessing .060 is larger so what's the best head gasket i can run?
 

turbofabricator

Well-Known Member
Cometic. Block deck and cylinder heads must be milled smooth to make 'em work, though. Stock machined deck surfaces are not smooth enough.
 

williamsGN

'Horse sneeze' addict
I've done three Cometic headgasket jobs with stock surfaces, no leaks. Even my short block builder at JMSracing.com said stock finish is fine. Don't know where this urban legend of needing special surfaces came from. Used studs and proper prep, no problems, maybe those with problems are missing steps.

Available from Summit.
 

Slow91z

Turbobuick.com Helper
Staff member
Not an urban legend the info comes from cometic...although i have also used them with stock surfaces.
 

williamsGN

'Horse sneeze' addict
Guess they are trying to cover their butts as far as sealing. Good thing I never read their site since it says to install them dry and I and everyone I know always used copper spray. Goes to show you get different results on different applications.
 

GNcincy87

Member
summit has gaskets with different compressed thickness (.040 .051 .060) . from my understanding the .040 would bump up compression just a hair over stock, and the others would lower it. what is the optimal CR i should go for or what compressed thickness??
 

williamsGN

'Horse sneeze' addict
I sprayed both sides with copper spray, didn't take the rivets out as some have. Used a bit of rtv around the holes for the water passages. I'd say the .040.
 
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