SCE Pro Seal Performance Composite Head Gasket for Small Block Chevrolet. Bore Opening: 4.200"; Compressed Thickness: .040"; Material: Graphite Facing on Steel Core with 321 Stainless Fire Ring Armor. Package Contents: 1 Piece. SCE Pro Seal composite head gaskets are simple but trick. These high performance head gaskets are constructed of three elemental components, pure graphite facing mechanically clinched to a perforated steel core with 321 stainless fire ring armor. Unlike other brands there is no o-ring behind the fire ring, this allows for a strong but compressible gasket which will not damage aluminum cyliders heads from fretting or friction brinelling. Yet the 321 stainless combustion seal is strong enough to withstand up to 15lbs of boost or a 100hp shot of nitrous.
