High output engines with high cylinder pressures require two piece articulated pistons. Refer to the parts book to obtain information about the type of pistons used in a specific engine.
The two piece articulated piston consist of an alloy forged steel crown connected to an aluminum skirt by the piston pin. The two piece articulated piston has three rings: one compression ring, an intermediate ring, and one oil ring. All the rings are located above the piston pin bore. The compression ring is of the KEYSTONE type, which have a tapered shape. The action of the ring in the piston groove, which is also tapered, helps prevent seizure of the rings caused by carbon deposits. The intermediate ring is rectangular with a sharp lower edge. The oil ring is a standard (conventional) type. Oil returns to the crankcase through holes in the oil ring groove.
Oil from the piston cooling jets spray the underside of the pistons. This lubricates and cools the pistons, and improves piston and ring life.
The connecting rod has a taper on the pin bore end. This gives the rod and piston more strength in the areas with the most load. Two bolts hold the rod cap to the rod. This design keeps the rod width to a minimum, so that the rod can be removed through the cylinder.