Tools Required

J 8087  Cylinder Bore Gage

Important:  Measurements of all components should be taken with the components at normal room temperature.

For proper piston fit, the engine block cylinder bores should not have excessive wear or taper.

A used piston and pin set may be reinstalled if, after cleaning and inspection, they are within specifications.

1. Inspect the engine block cylinder bore using the J 8087. 
   Fig 1: Identifying J 8087

   Courtesy of GENERAL MOTORS CORP.
2. Inspect the piston and pin. Refer to Piston, Connecting Rod, and Bearings Cleaning and Inspection  .
3. Use the J 8087  and measure the cylinder bore diameter. Measure at a point 64 mm (2.5 in) from the top of the cylinder bore.
4. Measure the J 8087  with a micrometer and record the reading.
   Fig 2: Measuring Cylinder Bore Diameter

   Courtesy of GENERAL MOTORS CORP.
5. With a micrometer or caliper at a right angle to the piston, measure the piston 11 mm (0.433 in) from the bottom of the skirt.
6. Subtract the piston diameter from the cylinder bore diameter in order to determine piston-to-bore clearance. Refer to Engine Mechanical Specifications  .
7. If the proper clearance cannot be obtained, select another piston and measure the clearances.
8. When the piston-to-cylinder bore clearance is within specifications, permanently mark the top of the piston for installation into the proper cylinder.
   Fig 3: Measuring Piston From Bottom Of Skirt

   Courtesy of GENERAL MOTORS CORP.