CAMARO6 - View Single Post - Stock Intake Valve Seat Failure on TSP PRC Ported Heads with Big Cam

cmitchell17 · 02-21-2021, 04:13 PM

My best guess is that both my intake and exhaust valve have burnt or have sealing issues. The backfiring out the intake valve is just because the intake valve is not sealing. At the same time I can feel both intake and exhaust rocker arms on the #7 and they are both loose, so the valve springs are pulling them shut as far as they can since pressure is off the rocker arm. It still only builds about 7 psi in the chamber though, and I think I can hear it at the tailpipe hissing.

At this point I guess I need to start ordering head gaskets, but I want to use this as an opportunity to upgrade and check piston to valve clearance at the same time. I want more compression since I run E85 100% of the time, my heads are supposed to be milled .030 which I have calculated that I should be around 12.25 but I want to see how much more I can get checking PTV and maybe trying a thinner head gasket. Anyone else out there running a thinner gasket on the LT1?

02-21-2021, 04:13 PM	#20
cmitchell17 Drives: 17 2SS, 8L90, Cam, Heads, E85 Join Date: Dec 2016 Location: US Posts: 1,204	My best guess is that both my intake and exhaust valve have burnt or have sealing issues. The backfiring out the intake valve is just because the intake valve is not sealing. At the same time I can feel both intake and exhaust rocker arms on the #7 and they are both loose, so the valve springs are pulling them shut as far as they can since pressure is off the rocker arm. It still only builds about 7 psi in the chamber though, and I think I can hear it at the tailpipe hissing. At this point I guess I need to start ordering head gaskets, but I want to use this as an opportunity to upgrade and check piston to valve clearance at the same time. I want more compression since I run E85 100% of the time, my heads are supposed to be milled .030 which I have calculated that I should be around 12.25 but I want to see how much more I can get checking PTV and maybe trying a thinner head gasket. Anyone else out there running a thinner gasket on the LT1?