[JoeC]

The Chevy Power book just gives the deck clearance as .035 minimum. Meaning you must maintain a minimum of .035 inch clearance between the piston and the cyl. head in any area where they may make contact. A composition head gasket may have a compressed thickness of .040 inch which would allow the piston to be above the deck .005. A steel shim gasket may have a compressed thickness of .022 which would allow the piston to be below the deck .013. These are minimum numbers. I know one engine builder that won't go below .060 deck clearance. An engine builder may use different numbers depending on experience and what parts they use. Is the NHRA number of .008 above or below the deck? NHRA may mandate that number for safety purposes. If the piston is .008 above the deck and your gasket is .040 only leaves .032 for clearance. I'm not sure why NHRA uses that number.