When overhauling your engine or cylinder head, it is important that every component that will be part of the final assembly meets the manufacturer specifications, including each cylinder valve, to prevent engine performance problems. Measuring valves will allow you to make important decisions about making cylinder head repairs, reusing or replacing the valves and other components. You can perform this check in your garage with a few precision tools before sending your engine to the machine shop for inspection.
Place the valve you want to measure on the clean surface of a workbench or working area so the valve is standing on its head with the stem pointing up.
Locate the valve’s margin. If you look at the base of the valve, you will notice its outer surface is formed at a 45-degree angle. This is called the valve face. At the bottom of the face, touching the surface of your workbench, you will notice a narrow band. This is called the valve margin.
Measure the width of the valve margin using a vernier caliper. In most cases, an exhaust valve should have a margin width of at least 0.030 in. An intake valve should have a margin width of at least 0.015 in. Compare your measurements with the specifications listed in the service manual for your particular vehicle make and model.
Measure the top, center and bottom of the exhaust and intake valve stems using an outside micrometer. When measuring the top of the stem, take your measurement below the groove at the top of the stem. Compare your measurements with the specifications listed in the service manual for your particular vehicle make and model.
Measure the valve head diameter using an outside micrometer. The valve head is the valve base, opposite the stem tip. Compare your measurements with the specifications listed in the service manual for your particular vehicle make and model.
