Valve Seat Width Measurement Procedure

WARNING: This page is about a different variant/trim than selected.

Fig 1: Measuring Valve Seat Width In Cylinder Head

Courtesy of GENERAL MOTORS COMPANY

Measure the valve seat width in the cylinder head using a proper scale.

Fig 2: Measuring Seat Width On Valve Face

Courtesy of GENERAL MOTORS COMPANY

Measure the seat width on the valve face (1) using a proper scale.

NOTE:

The seat contact area must be at least 0.5 mm (0.020 in) from the outer diameter (margin) of the valve. If the contact area is too close to the margins, the valve must be replaced.

Compare your measurements with the specifications listed in Engine Mechanical Specifications .
If the seat widths are acceptable, check the valve seat roundness using the Valve Seat Roundness Measurement Procedure.
If the seat width is not acceptable, you must replace the valve. Proper valve seat width is critical to providing the correct amount of valve heat dissipation.