Piston Fitting
The pistons are "select fit" to achieve proper oil clearance. Engine block cylinder bore diameter grade markings are stamped into the right side of the engine block. These marks are read from front to rear, corresponding with cylinder number 1, 2, 3, 4.
Engine block cylinder bore diameter grade markings correspond to specific cylinder bore diameters. The chart below identifies the three engine block grade markings and their associated cylinder bore diameters.
| Engine Block Marking | Cylinder Bore Size mm (in.) | |
|---|---|---|
| Metric | Standard | |
| A | 72.000 - 72.010 mm | 2.8346 - 2.8350 in. |
| B | 72.010 - 72.020 mm | 2.8350 - 2.8354 in. |
| C | 72.020 - 72.030 mm | 2.8354 - 2.8358 in. |
The piston is marked with the piston size (1) on the piston crown. The pistons are available in three different sizes in order to achieve the desired oil clearance. Select the piston size that corresponds to the engine block cylinder bore diameter grade markings for each cylinder.
Pistons are available in three sizes. The chart below identifies the three piston sizes.
| Piston Marking | Piston Size mm (in.) | |
|---|---|---|
| Metric | Standard | |
| A | 71.960 - 71.970 mm | 2.8331 - 2.8835 in. |
| B | 71.970 - 71.980 mm | 2.8835 - 2.8339 in. |
| C | 71.980 - 71.990 mm | 2.8339 - 2.8342 in. |
Typical coated piston shown in illustration.
The coated pistons are serviced with the piston pin and connecting rod pre-assembled. The coating material (1 and 2) is applied to the piston after the final piston machining process. Piston installation into the cylinder bore requires slightly more pressure than that required for non-coated pistons. The bonded coating on the piston will give the appearance of a line-to-line fit with the cylinder bore.