Edelbrock Performer RPM series aluminum heads for small block Chevy. Improved power throughout the rpm range for great throttle response and top-end horsepower. Features hardened interlocking valve seats for use with unleaded fuel. Completely assembled with stainless valves, positive oil control seals, screw in rocker studs, hardened guide plates, valve springs, retainers and keepers. Available in straight or angle plug configuration.