Drag Racing Online, September 2012: Why Tool Steel Flat Tappets Run Forever

Despite the popularity of the roller tappet both in a mechanical as well as hydraulic setting, typical flat tappets, also known as lifters or followers, are still as popular as ever. While a roller tappet utilizes a roller to roll along the camshaft’s lobe profile, a flat tappet simply rides directly on the lobe. To eliminate wear, the base of the flat tappet is ground on a convex shape and the cam lobe is tapered. The combination of the convex shape—which is almost indiscernible to the naked eye—and the tapered cam lobe forces the flat tappet to spin in the tappet bore of the engine.

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