The Edelbrock part # 61917 small-block Chevy LT1 (1992-97) Performer NHRA cylinder heads deliver 24 horsepower over stock and raise the peak power level by 500 rpm. These heads are designed to accept factory style self-aligning rockers. Performer LT1 cylinder heads are 50-state street legal and accept factory centerbolt valve covers. They feature exhaust ports in the stock location for use with stock or aftermarket exhaust manifolds and headers. Match with RPM Air-Gap intake #7107, throttle body #3809 and camshaft #2108 for the Total Power Package combo. - 61917 Cylinder Heads are allowed for use in the NHRA Super Stock class - Combustion chamber volume: 54cc - Intake runner volume: 170cc - Exhaust runner volume: 60cc - Intake valve diameter: 1.94" - Exhaust valve diameter: 1.55" INSTALLATION NOTE: Bare heads will have valve guides and seats installed, but will require final sizing and a valve job to match the valves you will be using. Recommended spark plugs are Champion RC12YC or equivalent 14mm x 3/4" reach with flat gasket seat. Match with Edelbrock head gasket sets.