37. Piston Selection

Important: Measurements of all components should be taken with the components at normal room temperature.
For proper piston fit, the engine block cylinder bores must 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 for scoring or other damage.
2. Inspect the piston and the piston pin.
Refer to Piston, Connecting Rod, and Bearings Clean and Inspect (Piston and Pin).
3. 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.
4. Record the piston diameter.





5. Adjust the micrometer to the recorded piston diameter.
6. Insert the bore gauge into the micrometer and zero the bore gauge dial.





7. Use a bore gauge and measure the cylinder bore diameter. Measure at a point 64 mm (2.5 inch) from the top of the cylinder bore.
8. Record the cylinder bore diameter.
9. Subtract the piston diameter from the cylinder bore diameter in order to determine piston-to-bore clearance.
The proper piston-to-bore clearance should be between 0.018 - 0.054 mm (0.0007 - 0.00212 inch).
10. If the proper clearance cannot be obtained, select another piston and measure for the clearances.
If the proper fit cannot be obtained, the cylinder bore may require honing for an oversize piston or block replacement.
11. When the piston-to-cylinder bore clearance is within specifications, permanently mark the top of the piston for installation to the proper cylinder.
Refer to Separating Parts.