CYLINDER
BLOCK
The Camshaft
and
Timing Gears. The camshaft is a high
carbon steel forging. The cam surface and journals are induc-
tion hardened to improve wear resistance. The shaft is sup-
ported on three bearings: the front bearing is a bush bearing
(with the exception
of
a bushless bearing for engines pro-
duced in the initial period
of
production), while the middle
and rear bearings are in the holes cut in the cylinder block.
All bearings are 'lubricated by a forced lubrication system.
The camshaft rear journal has a slot for intermittently lubri-
cating the rocker arms through the cylinder head. The rear
of
the shaft is provided with
an
oil escape hole to let excess oil
return to the oil pan.
The helical timing gears are finished by shaving and crown-
ing to provide high durability and to reduce chattering.
Valve timing is as follows.
T.D.C
INTAKE
VALVE
OPENS
EXHAUST
VALVE
CLOSES
VALVE
TIMING
EXHAUST
VALVE
OPENS
B.D.C
VALVE
TIMING
Intake
valve
opens
(BTDC)
18°
Exhaust
valve
closes
(ATDC)
18°
I
ntake
valve
closes
(ABDC)
46°
Exhaust
valve
opens
(BBDC)
46°
The tappet
and
push rod. The tubular type tappets are
chilI~
hardened at the bottom and gas-carburized at low tempera-
ture over the entire surface to improve wear resistance. Each
tappet is offset from the cam center to prevent uneven wear
of
the tappet bottom. The steel-bar push rods are flame-hard-
ened at each end.
-~II-I""'~-OFFSET
OFFSET
OF
TAPPET
AND
CAMSHAFT
The injection
pump
camshaft is made
of
high carbon steel.
Its cam surfaces are induction-hardened
to
improve wear
resistance. The front end
of
the shaft supported on a ball
bearing is connected to a gear. The rear end is provided with
an
Oldham's coupling groove for connecting to the oil pump
drive shaft.
The high-pressure oil
pump
is directly coupled
to
the
injec~
tion pump camshaft at the rear
of
the shaft, mating into the
Oldham's coupling groove.
The sheet metal oil sump has an oil drain hose that routes
from the lube oil drain plug to a bracket at the front side
of
the engine.
Engines & Generators
22
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