Measuring instruments and measurement

Figure 31.1(a) shows a feeler gauge in use, measuring valve clearance. In this example, the feeler gauge is being inserted between the heel of the cam and the cam follower, with the valve in the fully closed position. When ready to proceed with the measurement, the gauges of the required thickness are inserted in the clearance between the heel of the cam and the cam follower, and a light-hand force, sufficient to slide the feeler gauge through the gap, is applied.