COMP Cams CL12-600-4 Thumpr 227/241 Hydraulic Flat Cam and Lifter Kit for Chevrolet Small Block 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. 0.479"/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 Chevrolet GEN 1 Small Blocks including the 262, 265, 267, 283, 302, 305, 307, 327, 350 and 400. Does not fit LT1/LT4, or factory roller Small Blocks built from 1985 and newer. Made in USA