29. Piston Selection
^ Tools Required- J8087 Cylinder Bore Checking Gauge
Important: When fitting pistons, both the piston and the cylinder bore condition must be considered together.
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. Measure the cylinder bore taper with the J8087.
Maximum Taper 0.10 mm (0.004 inch)
2. Measure the cylinder bore out-of-round with the J8087.
Maximum Out-of-Round 0.10 mm (0.004 inch)
3. Measure the cylinder bore diameter with the J8087. Measure at a point 50 mm (1.96 inch) and at a point 95 mm (3.74 inch) from the top of the cylinder bore.
4. Measure the bore gauge with a micrometer and record the readings.
Maximum Cylinder Bore Diameter 84.050 mm (3.3090 inch)
5. Measure the piston diameter with a micrometer at a right angle to the piston pin, 26.5 mm (1.04 inch) from the piston skirt.
6. Subtract the piston diameter from the cylinder bore diameter in order to determine piston-to-bore clearance.
Piston-to-Cylinder Bore Clearance 0.02 - 0.04 mm (0.0008 - 0.0015 inch)
7. If the proper clearance cannot be obtained, select another piston and measure the clearances.
8. If the proper fit cannot be obtained, hone the cylinder bore, rebore and use oversize pistons, or replace the cylinder block. Refer to the Piston Selection Table Specifications.
9. Pistons are stamped with a number 1 or 2. This number represents the outer diameter of the piston. Pistons are available in 2 standard and 2 oversizes.
Standard Size Piston 83.970 - 83.980 mm (3.3059 - 3.3062 inch)
Standard Size Piston 83.980 - 83.990 mm (3.3063 - 3.3066 inch)
0.25 mm (0.0098 inch) Oversize Piston
84.220 - 84.240 mm (3.3157 - 3.3165 inch)
0.50 mm (0.0196 inch) Oversize Piston
84.470 - 84.490 mm (3.3256 - 3.3263 inch)
10. The cylinder block is color coded with either red or blue paint marks (1). This color represents the inner diameter of the cylinder. The piston and cylinder must be matched for correct piston fit.
11. A piston stamped with a number 1 should be installed to a cylinder painted red. A piston stamped with a number 2 should be installed to a cylinder painted blue. Refer to the Piston Selection Table Specifications.
^ A red paint mark represents a cylinder bore diameter of 84.01 - 84.02 mm (3.3075 - 3.3078 inch).
^ A blue paint mark represents a cylinder bore diameter of 84.00 - 84.01 mm (3.3071 - 3.3-074 inch).
12. 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.