Chevrolet 70 1969 Series, Shop Manual

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6V-53 DIESEL ENGINE 6C-3
FINAL TUNE-UP OPERATIONS
E X H A U S T V A L V E A D J U S T M E N T
The clearance between the valve rocker arm
bridge and the exhaust valve stem should be .024"
when the engine is at operating temperature. The
clearance is set with a feeler gauge inserted be­
tween one valve stem and the bridge, and the other
end of the bridge resting on the other valve stem.
Maintaining normal operating temperature,
160°F.-185°F., is particularly important when ad­
justing the valve clearance. If the engine is allowed
to cool off before setting any of the valves, the
clearance when running at full load may become
too small.
Insufficient valve clearance will result in loss
of compression, misfiring of cylinders, and even­
tual burning of the valves and valve inserts. E x ­
cessive clearance will result in noisy operation,
especially in the low speed range.
If the rocker arm bracket bolts, or cylinder
head bolts are disturbed for any reason, the ex­
haust valve clearance should be adjusted to .026"
before starting the engine. Then, recheck valve
clearance with gauge J-8311 after the engine has
reached its normal operating temperature.
All valve clearances can be adjusted during
one full revolution of the crankshaft.
With the engine at normal operating temper­
ature, to adjust the valves proceed as fallows:
1. Place fuel shut-down lever in th e N O ^F U E L
position.
2. Rotate crankshaft (using the startei?) until
the injector follower is fully depressed on the par­
ticular cylinder to be adjusted.
N O T E : If using a wrench on the crankshaft
bolt at the front of an engine, do not turn engine in
a left-hand direction, as the crankshaft bolt will
be loosened.
3. Loosen the push rod lock nut on one of the
valve push rods, shown in figure 1, for number 1
cylinder, and placing a .025” feeler gauge, tool
J-8311 between one valve stem and one end of the
rocker arm bridge, adjust the push rod to obtain
a smooth "pull” on the feeler gauge.
N O T E : Cylinder numbers are identified in
figure 2.
4. Remove feeler gauge and while holding the
push rod, tighten the lock nut.
N O T E : Only one feeler gauge placed between
one valve stem and the end of the rocker arm
bridge is required to adjust the clearance. The
other end of the bridge will rest on the other valve
stem during adjustment. When the feeler gauge is
removed both valves will have their proper clear­
ance.
Figure 1 — Adjusting Valve Clearance
5. Recheck clearance with feeler gauge, tool
number J-8311. At this time, the .023” feeler gauge
should pass freely between the end of one valve
stem and the rocker arm bridge and the .025"
feeler gauge should not Readjust as necessary.
6. Check and adjust remaining valves as out­
lined in Steps 2 through 5.
F U E L IN JE C T IO N TIM ING
A check of fuel injection timing is not norm­
ally required as part of engine tune-up procedure;
however, in cases when it is necessary to check
the timing in diagnosing trouble, refer to "Injec­
tion Timing," covered later in EN G IN E F U E L
S Y S T E M (SEC. 6M) for information on making the
timing check.
G O V E R N O R GAP A D J U S T M E N T S
These procedures are explained later in the
EN G IN E F U E L S Y S T E M (SEC. 6M) under " F U E L
R IG H T B A N K
© © ©
FRONT —
© © ©
LEFT B A N K
V
F IR IN G O R D E R
1L-- 3 R — 3 L — 2 R - 2 L — 1R
T - 2 9 6 0
Figure 2— Cylinder Numbering and Firing
Order 6V-53 Diesel Engines
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SHO P M ANUAL