Fits 1965-1990 Chevrolet 396-454 Mark IV Big Block. Round Ports, 2.40 Inch

Manufactured from high-temperature steel core/graphite faced exhaust material. Expanded steel core provides stability and maximum torque retention to eliminate gasket failure. Graphite facing provides excellent heat resistance and thermal conductivity to transfer heat away from the cylinder head. Conforms to and seals minor surface irregularities. High recovery material allows header or manifold flange to stay sealed if flange loses clamp-load. Can be trimmed if necessary for modified port applications. For original equipment replacement, high performance street, drag race and oval track use.