Cylinder Head - GM LS1 V8Combustion chamber 64ccIntake runner 210ccExh Runner 82ccIntake Valve Dia. 2.020"Exh Valve Dia. 1.60"Valve Stem Dia. 0.316"Valve Stem Material Maganese BronzeThese castings feature a revised increased flow intake port design that must have appropriate sealant used on the factory rocker arm bolts to avoid vacuum leaks through the valve covers. Late model larger valve design requires the use of 2.02” intake and 1.60” exhaust valves.Pushrod length must be checked prior to running as with piston to valve clearance.