Cam duration helps to determine what point in the power band you'll get the best performance;
220 to 230 will produce the best low end performance.
240 to 250 duration will produce the best mid range performance.
260 duration and up will produce the best top end horsepower.
Duration is the amount of time in crankshaft degrees that the valve is open (at a specified amount e.g.: .053"), while the lifter is in motion.
An increase in compression ratio or a decrease in camshaft duration will increase cylinder pressure.
Lift helps produce torque and horsepower (up to the point at which the heads no longer flow effectively).
Overlap of thirty degrees or less normally produces the best low end.
The tighter the centerline the shorter the power band; the wider the centerline the wider the power band.
When installing a new cam always put a thin coat of a non-moly type assembly lube onto all machined metal surfaces and install a new Torrington bearing. Check cam cover to case alignment, as well as cam bushing and bearing fit, and check tappet rollers for any unusual wear and replace as necessary.
Cam end play should be no less then .003 and no more then .015.
Always check cam gear to pinion gear fit .
If the cam gear pitch is to tight to the pinion gear pitch, the gears will produce a whine. If the gear pitch is to loose it may produce a sound similar to lifter noise.
Some parts contained herein may not be legal for sale or use in California on any pollution controlled motor vehicles.