COMP Cams CL51-600-5 Thumpr 227/241 Hydraulic Flat Cam and Lifter Kit for Pontiac 265-455 High performance street, stock converter ok, best with 2000+ converter and gears. Choppy/thumping idle. 2,000-5,800 RPM Operating Range 227/241 Duration at .050". 107 Degree Lobe Separation Angle. 0.478"/0.465" Valve Lift CL Kits include a camshaft, a set of lifters, instructions and assembly lubricant. Early intake valve opening and long exhaust duration create optimum overlap for powerful, hard-hitting exhaust note. Best with aftermarket converters and more rear gear. Perfect choice for muscle cars and street rods - Three unique cam designs: Thumpr, Mutha' Thumpr and Big Mutha' Thumpr deliver excellent horsepower gains and broad torque curve. Fits Pontiac 265-455 V8 Made in USA