139651 - Crane Cams PowerMax Hydraulic Roller Cams Details

Chevy 396-454ci Big Block 1965-96

*Note: In order to use these camshafts in 1965-66 396/427ci blocks, it is necessary to machine a 3/16'' wide x 7/64'' deep groove in the rear main journal of the cam to allow oil flow to the top of the engine.

**Note: 1991-95 Gen-V engines can use these camshafts and components if they are converted to adjustable rocker arms by installing p/n 270-99152-16 rocker arm studs (no machining required) and appropriate rocker arms. Custom length pushrods can also be made to achieve correct lifter preload if standard non-adjustable rocker arms are retained.

***Note: Requires cam button spacer, camshaft incorporates an integral cast iron distributor drive gear, aluminum-bronze distributor drive gear not required. For engines equipped with mechanical fuel pump pushrod p/n 270-11985-1 is highly recommended to prevent fuel pump lobe wear. Some 1973 thru 1981 454ci engines were equipped with exhaust valve rotators. In these instances when using dual valve springs, use either our p/n 270-99459-8 spring seat spacers or only 8 of p/n 270-99948-16 (set of 16) valve spring retainers (on the exhaust valves only) to prevent excessive valve spring shimming when eliminating the rotators. Some later engines were equipped with rotators on both the intake and exhaust valves. For these applications when using dual valve springs, use either 2 of p/n 270-99459-8 spring seat spacers or p/n 270-99948-16 valve spring retainers to prevent excessive valve spring shimming when eliminating the rotators.

ROUGH IDLE, PERFORMANCE USAGE, GOOD MID AND UPPER RPM HP, BRACKET RACING, AUTO TRANS W/3500+ CONVERTER, MARINE PERFORMANCE, 3800-4200 CRUISE RPM, FOR 500+ CU. IN. ENGINES, 10.5 TO 12.5 COMPRESSION RATIO ADVISED.

Grind Number:	HR-306-2S-14 IG
Operating Range:	3800-7200 RPM
Duration Advertised:	306° Intake / 318° Exhaust
Duration @ .050'' Lift:	244° Intake / 256° Exhaust
Valve Lift w/1.7 Rockers:	.632'' Intake / .632'' Exhaust
Lobe Separation Angle:	114°
Max Lift Angle:	109° ATDC Intake / 119° BTDC Exhaust
Open/Close @.050'' Cam Lift:	Intake - 13° BTDC (opens) / 51° ABDC (closes) Exhaust - 67° BBDC (opens) / 9° ATDC (closes)