With the high compression ratio of the pre-chamber diesel, there is minimal valve-to-piston clearance. Because it is important to have a rigid valve train that insures a precise valve train motion through the speed range, a shaft supported valve rocker arm design is used. Nodular iron rocker arms with a steel backed bushing are used. The shafts are bolted to case stanchions on the cylinder head. The design has a steel backed bronze alloy bushing in the rocker arm which is final bored after being press fit into the cast arm. This bushing uses a performed circumferential oil groove and 2 cross oil grooves for directing lubrication to the mating shaft surface. Oil is supplied to the rocker arm via the hollow push rod and the arm in turn has drilled passages that provide a flow path for oil to the bushing.
The 1982 engine used a hardened steel spacer and a metric washer at the rocker shaft attachment. The 1983-84 engine uses an unhardened spacer and a steel cleat. The steel cleat has a large gap 90° to the bolt. This prevents any closure, and the cleat spreads the load.
Spacer part # — New 14057297
— Old 14028990
1983-84 Cleat — 14057296
1983-84 Rocker Arm Assembly 14061505
