My last manifold gasket burned out on a '68 292 L6 w/Clifford headers and Offy intake. Manifolds got loose after 600 miles of break in. I forgot to tighten the headers regularly and an air leak occurred, the Holley backfired -- the power valve got blasted and then I had to limp home. Tearing down the carb and manifolds today, I found the gasket was burned (charred) at the #4 + 5 exhaust ports, and the bottom of the gasket was blasted away.
I have a new Clifford header gasket but I am wondering if I should coat it with Permatex Copper Spray-A-Gasket or leave it dry like the guy at the speed shop said. Last time a different guy at the same speed shop told me to dab a small bead of Ultra Copper RTV around all the holes. That didn't work too well. I like the idea of reinforcing a basically cardboard (composition?) gasket with something metallic.
Also I tried to recycle the same 28-year-old header bolts. Having now re-inspected the threads, I will definately replace them with Grade 8 fasteners, at least.
What do you guys think?
I/I #4101
'71 GMC Jimmy 350, sm465, np205,3.73 posi.
'68 C/10 Stepside 292 (.030 over) Offy Intake, 500 CFM AFB,Clif headers, sm465, 3.73 posi.
'67 K/10 454 project.
'72 K/5 rolling frame project.
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