Head Gasket SetBig-Bore 351W Ford Racing BlocksBore Diameter: 4.125'Gasket Diameter: 4.160'Compressed Thickness: 0.040'Compressed Volume: 9.1cc 4.125' overbore competition gasket. Same as gasket (M-6051-D331) except designed for Ford Racing blocks with larger 4.125' overbore. Bore flange valve pockets have been added to unshroud intake and exhaust valves. Set includes unique right- and left-hand gaskets!Ford Racing performance cylinder head gaskets minimize blowout and have a wire-ring combustion seat for extra sealing around combustion chambers. Ford Racing performance cylinder head gaskets are available with either steel-core laminate construction for cast iron heads, or graphite cores with a pre-flattened steel-wire ring, so they wont brinell aluminum heads.4.125 in. Overbore Competition GasketBore Flange Valve Pockets Have Been Added4.125 in. Bore Diameter4.160 in. Gasket Diameter0.040 in. Compressed Thickness9.1cc Compressed VolumeMade in the USA