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6A4-2
1977 PONTIAC SERVICE MANUAL
Fig.
6A4-1 3 5 0
(VIN R) and
4 0 3
(VIN K) Engines (Exploded View)
Fig.
6A4-2
Cylinder Numbers
ENGINE LUBRICATION SYSTEM
(Fig. 6A4-3)
The engine oil pan forms a reservoir for engine oil to
provide lubrication and also hydraulic fluid to operate the
valve lifters. Oil pressure for lubrication is furnished by a gear
type oil pump that is bolted to the rear main bearing cap and
driven by the camshaft gear through a hexagonal drive shaft.
Oil enters the pump through a screened inlet located
near the bottom rear of the oil pan. The pressurized oil from
the pump passes through the oil filter located on the right rear
side of the engine block. The oil filter base has a by-pass valve
which in the event of filter restriction will open at 5.3 to 6.3
psi. Oil then enters the right oil galley where it is distributed
to the five main bearings. The right bank valve lifters receive
oil from this galley from eight feed holes that intersect the
galley.
The five camshaft bearings are lubricated from vertical
passages intersecting the main bearing oil passages. At the
front main bearing a third passage connects the right main
oil galley to the left galley which then feeds the left bank of
valve lifters.
The engine oil pressure warning light switch is connected
to the front of the left oil galley. The switch is calibrated to
turn on the instrument panel warning light when engine oil
pressure is too low. The switch, normally closed, is set to open
at 2-6 psi. The rear oil galley plug has a .040" orifice to help
purge contaminants from the galley.
The front end of the right galley, a small orifice sprays
oil to lubricate the fuel pump eccentric cam and the timing
chain.
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