Head gaskets feature a steel tang core laminated on both sides with flexible graphiteAll fan-cooled and free-air engines come with a graphite head gasket; all liquid-cooled engines come with a composite-fiber head gasket except O-ring or bumped-metal head. CFM-20, A perforated steel core with an elastomer surface is ideal for head gaskets allowing heat to be drawn evenly across the gasket surface while providing maximum sealing characteristics when exposed to coolants and oils. Available thickness: .043”, .059".
