26. Piston Selection

^ Tools Required
- J 8087 Cylinder Bore 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 must not have excessive wear or taper.
Clean and inspect a used piston and a used pin set. If the piston and the pin set are within specifications, you may reinstall these items.





1. Inspect the engine block cylinder bore.
Refer to Engine Block Clean and Inspect.
2. Inspect the piston and the piston pin.
Refer to Piston, Connecting Rod, and Bearings Clean and Inspect (Piston/Connecting Rod Inspect)
3. Use a J 8087 in order to 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 with calipers at a right angle to the piston, measure the piston 25 mm (1 inch) from the top of the piston.
6. Subtract the piston diameter from the cylinder bore diameter in order to determine piston-to-bore clearance.
7. For proper piston-to-bore clearance.
Refer to Specifications.
8. If the proper clearance cannot be obtained, select another piston, and measure the piston for the clearances.
9. If the proper fit cannot be obtained, hone the cylinder bore, or replace the cylinder block.
10. 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.