What tool is used to check the gap between the bucket and the cam lobe?

• A. Feeler Gauge
• B. Caliper
• C. Micrometer
• D. Dial Indicator

Answer: (A)

Measuring valve clearance in the valve train requires a tool that can fit into a very small gap and give a precise thickness. A feeler gauge provides thin blades with accurately known thicknesses, so you can try different blades between the bucket and the cam lobe until one just fits. That blade’s thickness is the actual clearance value. Calipers and micrometers are better for overall dimensions of parts, not for directly reading a tiny, internal gap, and a dial indicator measures displacement rather than a direct gap between two surfaces. So the feeler gauge is the standard choice for this measurement.