COMP Cams 01-421-8 Xtreme Energy 236/242 Hydraulic Roller Cam for Chevrolet Big Block GEN VI Street/strip applications with 10:1+ compression and 2800+ stall. Rough idle, needs good intake and headers. 2,500-6,000 RPM Operating Range 236/242 Duration at .050". 110 Degree Lobe Separation Angle .521"/.540" Valve Lift Excellent performance in street carbureted applications. Quicker opening lobe profiles deliver increased responsiveness and more area under the lift curve. More vacuum allows an increase in duration for improved performance and assists power brakes. Best performance with aftermarket intake manifolds, headers and lower gear ratios. Fits Chevrolet 454/502 Mark VI Big Block w/ OE Roller Camshaft