Pistons And Connecting Rods
| ITEM | DESCRIPTION |
|---|---|
| 1 | Upper compression ring |
| 2 | Lower compression ring |
| 3 | Oil control ring |
| 4 | Circlip |
| 5 | Piston |
| 6 | Connecting rod |
| 7 | Large end bearing - Upper |
| 8 | Connecting rod bearing cap |
| 9 | Bolt - Connecting rod bearing cap (quantity 2) |
| 10 | Large end bearing - Lower |
| 11 | Small end bearing |
| 12 | Circlip |
| 13 | Gudgeon pin |
The connecting rods are manufactured from forged steel and have fracture split connecting rod bearing caps to make sure precision reassembly for bearing alignment. The connecting rod bearing caps are not selectable. Adjustment for large end bearing journal size is made by selecting the correct large end bearings after measuring the crankshaft journals.
There are a number of grades of large end bearing available. Each size of the bearings is inject marked with a letter on the running face of the bearing. The crankshaft is laser etched with a string of 4 alpha characters in the order of crankshaft journals 1-4. A data matrix code contains the reference data for each large end bearing, installed to the engine. The correct large end bearings are sized with reference to a selection chart in order to achieve optimum running clearances.
For additional information, Refer to: SPECIFICATIONS
There is only 1 grade of piston diameter. The top face of the pistons are marked with an arrow that must point towards the front of the engine to assure correct assembly. The piston crown has a recess for optimization of the fuel/air mixture and combustion.
The pistons use a 3 ring piston sealing system. An oil control ring is located in the lower groove. The 2 compression piston rings are located above the oil control ring. The piston ring gaps must be positioned at 120° to each other. The pistons are cooled with engine oil from 4 piston cooling oil jets installed in the cylinder block.
The pistons are attached to the connecting rods with a gudgeon pin, which is secured with 2 circlips. The gudgeon pin is located through the small end bearing in the connecting rod which allows the piston to articulate with the linear movement of the connecting rod. The 2 circlips locate in grooves in the piston.