Re: cam specks

[Duke Williams (22045)]

The L-71/72 cam should meet your requirements. I have the following data for the Speed Pro CS-165R, which is billed as a clone to the L-72 cam.

SAE J604d (.006" valve lift)

41-88/83/32, 309/295, 108/120/114, .306"/.306" lobe lift .020"/.024" lash

Duration at .050" tappet lift: 242/242

The J604d duration looks rather long compared to the .050" tappet lift duration. This is because this cam has very soft action to be easy on the valve train.

Idle vacuum should be no less than 14"@900. Make sure you use a vacuum can that provides full vacuum advance at no less than 12" and be sure that the vacuum source is full manifold vacuum, not "ported" vacuum. The early phased exhaust lobe is specfically designed for the OEM exhaust manifolds.

Duke

[John Lokay]

Re: cam specks

Duke, you stated that the "cam has very soft action to be easy on the valve train". What does this mean?

[Duke Williams (22045)]

Re: cam specks

"Soft action" refers to modest acceleration characteristics. The difference in .050" duration, J604d duration, and lash point duration provides a clue. The larger the difference, the softer the action.

Chevrolet SHP cams are soft action because they are designed for street engines with the same longevity as base engine cams. Aftermarket cams and true racing cams often have more aggressive action - faster acceleration, which can improve top end power for the same timing, but will take some measure of life out of the valve train.

This is one reason why I like OE cams for street high performance engines. Unless you screw-up, you aren't going to be replacing broken valve springs, bent pushrods, and camshafts with wiped out lobes.

Duke