Piston Selection

PISTON SELECTION (UNIT REPAIR)

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.
2. Inspect the piston and the piston pin.





3. 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.
4. Measure the bore gauge with a micrometer and record the reading.





5. With a micrometer or caliper at a right angle to the piston, measure the piston 14 mm (0.570 inch) from the bottom of the skirt.
6. Subtract piston diameter from the cylinder bore diameter in order to determine piston-to-bore clearance.
7. Proper piston-to-bore clearance is 0.010 - 0.041 mm (0.0006 - 0.0016 inch).
- If proper clearance cannot be obtained, select another piston and measure clearances.
- If proper fit cannot be obtained, hone the cylinder bore or replace the cylinder block.
8. When the piston-to-cylinder bore clearance is within specifications, mark the top of the piston using a permanent marker for installation to the proper cylinder.