Fitting Pistons
- Check block for distortion, cracks, scratches or other abnormalities. Measure bores at top, center and bottom of piston ring travel for taper and out-of-round. See Fig 1 .
- If any cylinder is tapered, out-of-round or cylinder walls are badly scuffed or scored, block must be bored or honed and new oversized pistons and rings installed. See CYLINDER BORE SPECIFICATIONS
table.CYLINDER BORE SPECIFICATIONS
Piston Size Cylinder Bore: In. (mm) Limit: In. (mm) Standard 3.0315-3.0330 (77.000-77.040) 3.0394 (77.200) .50 Oversize 3.0512-3.0528 (77.500-77.540) 3.0590 (77.700) 1.0 Oversize 3.0709-3.0724 (78.000-78.040) 3.0724 (78.040) - Bore or hone all cylinders to same oversize. DO NOT bore only one cylinder. Bore or hone cylinders in sequence, skipping adjacent cylinders to prevent heat distortion. Standard pistons are available in 4 sizes and oversize in 2 sizes for non-turbo and turbo engines. Piston identification marks are located on top of piston. See STANDARD PISTON APPLICATION table.
STANDARD PISTON APPLICATION
| Size Mark | In. (mm) | |
|---|---|---|
| Non-Turbo | ||
| A | 3.0303-3.0307 (76.970-76.980) | |
| B | 3.0307-3.0310 (76.981-76.990) | |
| C | 3.0311-3.0314 (76.991-77.000) | |
| D | 3.0315-3.0318 (77.001-77.010) | |
| 0.5 Oversize | 3.0490-3.0498 (77.445-77.465) | |
| 1.0 Oversize | 3.0687-3.0695 (77.945-77.965) | |
| Turbo | ||
| A | 3.0295-3.0299 (76.950-76.960) | |
| B | 3.0299-3.0303 (76.961-76.970) | |
| C | 3.0303-3.0307 (76.971-76.980) | |
| D | 3.0307-3.0311 (76.981-76.990) | |
| 0.5 Oversize | 3.0496-3.0499 (77.460-77.470) | |
| 1.0 Oversize | 3.0692-3.0697 (77.960-77.970) | |
NOTE:
Oversize pistons are stamped on crown to indicate oversize.