Camshaft Comparison - Cam Tech

Hydraulic Flat-Tappet vs. Mechanical RollerThis test originally appeared in our November '00 issue with the plan to pit a typical flat-tappet hydraulic cam against a more aggressive mechanical roller. While most car crafters will recognize that this is anything but a fair fight, the concept was not to see who wins, but rather how much of a difference the mechanical roller cam is worth. The follow-up question then becomes, is the gain worth the additional price of the roller? The guinea pig for this test was a Steve Dulcich-built 440ci Mopar using a set of ported mid-'70s 742 iron castings, a Mopar Performance M-1 intake, an 850-cfm Barry Grant Speed Demon carb, and a set of 171/48-inch Hooker headers flowing through a pair of Flowmaster mufflers.

The difficulty with doing this story is coming up with a fair comparison, which in reality is not easy because the mechanical cam has lash figures of 0.016 and 0.018 inch, which do not allow comparing advertised duration at, say, 0.006-inch of tappet lift. The duration-at-0.050 numbers indicate that the mechanical roller is much "bigger" but most of that is inherent in the roller design, the exact concept this test was intended to evaluate. The included cam-specs chart indicates how much more aggressive the mechanical roller cam is merely by evaluating the differences in valve lift. The mechanical roller comes in with almost 0.070 inch more max valve lift that certainly contributes to the significant power increase inherent with a mechanical roller cam.

Is this truly a fair test? We'll let you decide. A concrete result of this apple-to-oranges comparison is that the roller cranked out over 20 lb-ft and 20 hp more average power with a peak horsepower difference well over 60 hp. Those are numbers that are hard to ignore as long as your wallet can accommodate the price of admission.

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