Valve Lifters and Guides Cleaning and Inspection

J 26900-2  Micrometer

Fig 1: Measuring Lifter Bore Diameter
Courtesy of GENERAL MOTORS CORP.
1. Use a caliper gage to measure the lifter bore diameter of the cylinder head.

   Lifter Bore Diameter:  31.000-31.025 mm (1.2205-1.2215 in)

Fig 2: Micrometer
Courtesy of GENERAL MOTORS CORP.
2. Use a J 26900-2  and measure the lifter diameter.

   Lifter Diameter:  30.966-30.976 mm (1.2191-1.2195 in)

3. Subtract the lifter diameter measurement from the lifter bore diameter measurement to determine the oil clearance.
   • Standard Oil Clearance:  0.024-0.059 mm (0.0009-0.0023 in)
   • Maximum Oil Clearance:  0.079 mm (0.0031 in)
4. If the oil clearance is greater than the maximum, replace the lifter. If the proper oil clearance is still greater than the maximum allowed, replace the cylinder head.