The crankshaft is a balanced, forged steel unit. Four cylinder engines have 5 main bearings. Six cylinder engines have 7 main bearings. The lower bearing shells are all the same. All of the upper bearing shells are also the same with the exception of the journal adjacent to the rear one. The next to the last journal is fitted with a flanged upper bearing shell. The flanges control the end thrust of the crankshaft.
The upper bearings have three holes in them. The middle hole receives lubricating oil from the main oil rifle. One of
the adjacent holes is aligned with a drilling to the camshaft journal and serves as an orifice for lubrication flow
to the journal. The other adjacent hole supplies lubricating oil for piston cooling. The hole does not align perfectly
with the cooling nozzle. The hole is off-set to keep it away from the highly loaded bearing area.
NOTE: Oversize service main bearings are available for re-ground crankshafts.
