Fitting Pistons & Rings

Inspect cylinder block for cracks or flaws. Using bore gauge, measure cylinder for out-of-round or excessive taper. If cylinder bore out-of-round or taper exceeds .0008" (.020 mm), refinish cylinder bore. When any one cylinder is bored, all cylinders must be bored. Check cylinder block-to-head contact surface for warpage. Maximum warpage limit is .002" (.05 mm).

Determine piston oversize according to amount of wear in cylinder. Measure piston diameter at thrust face. Add piston-to-cylinder clearance. Finish hone of cylinder may then be determined. See PISTON & BORE SPECIFICATIONS table.

NOTE: Pistons and rings are available in .020" (.50 mm), .030" (.75 mm) and .040" (1.0 mm) oversize for service.

PISTON & BORE SPECIFICATIONS

Piston Size		Diameter In. (mm)
Standard		3.3061-3.3073 (83.975-84.005)
0.020" (.50 mm) O/S		3.3258-3.3270 (84.475-84.505)
0.030" (.75 mm) O/S		3.3356-3.3368 (84.725-84.755)
0.040" (1 mm) O/S		3.3455-3.3466 (84.975-85.005)
Bore Size
Standard		3.3071-3.3073 (83.975-84.005)
Wear Limit		3.3181 (84.280)
Overbore Limit		3.3480 (85.040)

After honing cylinder to final fit, measure piston-to-cylinder clearance with piston and cylinder at room temperature of 70°F (20°C). Maximum clearance is .002" (.05 mm). Ensure bore difference between cylinders is .002" (.05 mm) or less. If more than specification, cylinders must be bored.
If pistons are reused, decarbonize piston and ring grooves with scraper or piece of broken ring. Clean oil slots in bottom land of oil ring groove. Check for scratches, wear or damage.
Measure side clearance of rings in grooves as each ring is installed. If side clearance exceeds specification, replace piston and rings. Check ring end gap. Install ring squarely in cylinder, using piston. When installing piston rings, ensure code mark on ring faces up.