39. Piston Selection

^ Tools Required
- J8087 Cylinder Bore Checking Gauge

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.
2. Inspect the piston and pin. Refer to Piston, Connecting Rod, and Bearings Clean and Inspect.





3. Use the J8087 and measure the cylinder bore diameter. Measure at a point 64 mm (2.5 inch) from the top of the cylinder bore.





4. Measure the J8087 with a micrometer and record the reading.





5. With a micrometer or caliper at a right angle to the piston, measure the piston 11 mm (0.433 inch) 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 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.