Buick LeSabre 1965 Service Manual page 38

2 - 1 6 ENGINE DESCRIPTION
ENGINE
Oil Filter. The AC full flow type
oil filter is externally mounted
on the right side of crankcase.
The filter permits rapid passage
of oil with a minimum drop in
pressure. Normally, ALL engine
oil passes through the filter ele-
ment. If the element becomes
restricted enough to produce
4-1/2 to 5-1/2 pounds difference
in pressure between the inlet and
outlet ports of the filter, a
spring-loaded ball type valve in
the filter base will open to by-
pass the element and route oil
directly into the main oil gallery.
Main Oil Gallery. The main oil
gallery runs full length of the
crankcase in the angle below the
camshaft. Through connecting
passages drilled in the crankcase
it distributes oil at full pressure
to all crankshaft and camshaft
bearings, from which oil is then
distributed to all other working
parts of the engine. See Figure
2-12. See 2-13 for 300 cu. in.
engine.
Crankshaft, Rods, and Pistons.
Holes drilled in the crankshaft
carry oil from the crankshaft
bearings to the connecting rod
bearings. Pistons and cylinder
walls are lubricated by oil forced
through a small notch in the bear-
ing parting surface on connecting
rod, which registers with the hole
in the crankpin once in every
revolution. Piston pins are lubri-
cated by splash.
Timing Chain and Sprockets. A
small amount of oil which escapes
from the camshaft front bearing
flows down the front face of the
cylinder crankcase to drop on the
crankshaft sprocket, from which
OVERSIZED
BOLT HOLE
VALVE LIFTER
OIL GALLERIES
MAIN OIL
GALLERY
OIL FILTER
Figure 2-12—Schematic Diagram of Engine Oil Flow (401 & 425 Cu. In. Engines)