Chain drive. 538 CAM - Aggressive camshaft with a "nasty" sound. This camshaft revs up fast and pulls hard in engines with big bore cylinders; modified cylinder heads; intake; compression and exhaust. The REAPER 538 grind will shine in 124" and larger cubic inch engines with added compression ratio. Ported cylinder heads are not required but will complement the cam and add even more pulling power throughout the range. The stock throttle body produces an excellent powerband and use of a high flow throttle body will increase peak power numbers. A high flow exhaust system and air cleaner is highly recommended for optimal performance. FEULING recommends matching this cam with our RACE SERIES oiling system.NOTE: High Lift valve springs are required on stock cylinder heads; see FEULING BEEHIVE valve spring kit 993530 or 588021. SE cylinder heads have high lift valve springs but will need to be verified. Heavy Duty one piece pushrods are also highly recommended see 993528.RPM range 2;350 - 5;975. Grind: 538..................Valve Lift Open Close Duration @ 50" lift @ TDC Lobe CenterlineIntake .538 20.5 BTDC 38.5 ABDC 239 .180 99 Exhaust .542 48 BBDC 18 ATDC 246 .157 105Overlap: 38 *Cam specs measured in the engine on the lifter @ 0.050" using a 1.61