Piston And Connecting Rod Orientation
| ITEM | DESCRIPTION |
|---|---|
| 1 | Piston and connecting rod assembly, cylinders 4-6 |
| 2 | Piston and connecting rod assembly, cylinders 1-3 |
| 3 | Bolts (12 off) |
| 4 | Connecting rod bearing cap (6 off) |
| 5 | Connecting rod lower bearing (6 off) |
When installing a connecting rod, ensure the back of the connecting rod faces the center of the 'vee'.
The pistons are fitted with 3 rings. The piston crown incorporates a pronounced bowl; this forms the combustion chamber, which promotes swirl and turbulence necessary for good combustion and improved emissions. In addition, the piston skirt has a molybdenum-coated surface, which counteracts scoring of the cylinder bore and piston.
The piston also incorporates a double wave gallery within the piston crown to enhance piston cooling. The pistons are supplied oil by means of spray jets located in the cylinder block oil gallery. These jets ensure optimum piston cooling to counteract the high temperatures generated by the combustion process.
Each piston is installed on a piston pin located in a bushing in the connecting rod.
| ITEM | DESCRIPTION |
|---|---|
| 1 | Ring gap oil control |
| 2 | Ring gap upper compression |
| 3 | Spiral joint oil control |
| 4 | Ring gap lower compression |
| 5 | Upper compression ring |
| 6 | Lower compression ring |
| 7 | Oil control ring |
When installing pistons ensure the arrows on the piston crowns all point to the front of the engine. All pistons are common single grade/single part number for all engines.
The piston top ring is a taper type and is fitted with the taper to the top of the piston. All rings marked 'top' are assembled with 'top' uppermost. All rings must be spaced evenly around the piston before installing. The circumference gap of the double beveled oil control ring must be opposite the spiral control joint.