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How to Measure a Camshaft Lift

by C.L. Rease

A camshaft controls the height and the duration of lift for the valves in the heads of your engine. The distance a camshaft lifts the engine valves depends on the size of the camshaft lobes. As the camshaft turns, a pushrod moves along the lobe in an elliptical pattern. When the pushrod sits on the rounded section of the lobe, the valve sits in its closed position. As the pushrod moves over the tapered section of the lobe, the valve opens. Knowing the camshaft lift--lobe length--allows you to setup your engine for maximum performance.

Spray carburetor cleaner on the camshaft lobes. Allow the cleaner to sit on the camshaft for five to 10 minutes. Wipe the oil residue and carburetor cleaner from the camshaft with a rag.

Open the jaws of a Vernier caliper. Slide the open jaws over the round end of a camshaft lobe. Close the caliper jaws until each jaw sits tight to one side of the lobe. Write down the measurement.

Open the jaws of the caliper. Place the bottom caliper jaws on the rounded end of the camshaft lobe. Push the top jaw tight to the top point of the lobe taper. Write down the measurement.

Subtract the rounded lobe dimension from the taper dimension. The difference between the two measurements equals the lift of the camshaft.

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