[B4C]

Originally Posted by KirkEvil

You need to find out head gasket thickness.

You need to know cam duration @ .006 lift to calc/estimate DCR. I dont see a shelf-available grind come up in googling those specs so Im guessing its a custom cam that may have proprietary lobes. My best guess based on comps lobe charts I am coming up with the following:

Assume 63cc, .005" OOTH, 74.5 IVC @.006, 0.030" gasket (concerning piston clearance):
12.07:1 SCR
8.87:1 DCR

Assume 63cc, .005" OOTH, 74.5 IVC @.006, 0.040" gasket (My preference):
11.77:1 SCR
8.66:1 DCR

Assume 63cc, .005" OOTH, 74.5 IVC @.006, 0.045" gasket:
11.63:1 SCR
8.56:1 DCR

Assume 63cc, .005" OOTH, 74.5 IVC @.006, 0.051" gasket (stock gasket thk):
11.46:1 SCR
8.44:1 DCR

Where did you get the 11.9:1 SCR from?

My general research:
91 octane: 8.5:1 DCR
92 octane: 8.5-8.6:1 DCR
93 octane: 8.7-8.8:1 DCR

Personally Ive run 8.88:1 DCR on an LS1, and 8.72:1 on an LS2 without issues running 93 pump.

I did not calculate the 11.9:1. Is there a way to measure the head gasket with it installed. I'll pull the rear cover and see if the cam has a serial number or something. He said it was a custom grind.