TM 9-4940-421-14
tinue turning until the leading edge of the marked vane
cessive clearance between the valve guides and stems,
on the flywheel is in line with the centerline mark on
or that excessive amounts of oil are entering the com-
the flywheel shroud of the no. 1 cylinder (fig 4-4). The
bustion; check the distributor and spark plug cables for
no. 1 piston is on top dead center in this position.
defects that could result in too inadequate a spark.
Replace distributor.
Burned or overheated plugs are indicated by a burnt or
(4) Remove the distributor cap. The centerline of
badly eroded electrode. Check the air shrouds and cool-
the distributor rotor should be in line with the center of
ing fins for causes of engine overheating. A rusty
the notch in the distributor housing. The no. 1 cylinder
brown or grayish white powdery deposit when
is ready to fire in the retarded timing position, when
unleaded or regular gasolines have been used is normal.
the distributor rotor is in this position.
Clean deposits from the electrodes. Use a wire brush to
(5) With the advance arm clamp screw loose, turn
clean the threads.
the distributor body slightly in a counterclockwise
(3) Examine the spark plug electrode for pitting.
rotation so that the breaker points are firmly closed.
Replace a badly pitted spark plug.
Then turn the distributor body in a clockwise rotation
(4) Set the gap of spark plugs to 0.030 inch.
until the breaker points are just beginning to open. At
c. hstallation. Install spark plug and gasket in the
this point a slight resistance can be felt. Tighten ad-
spark plug hole and tighten. Torque the spark plugs
vance arm clamp screw.
25-30 lbs. ft. Connect the spark plug cables.
(6) The breaker point gap should be 0.018 to 0.022
inch. This should be checked before the distributor body
a. Removal.
is set, otherwise any adjustment made to the breaker
(1) Remove eight bolts and eight nuts and remove
point opening will change the ignition advance.
false panel (compartment 1).
Replace the distributor cap. If care is exercised in the
(2) Loosen hose clamp on carburetor air intake.
above operations, the spark timing should be accurate
(3) Remove eight bolts and eight lockwashers
enough for satisfactory operation, checking spark ad-
securing screen and air intake duct. Remove flywheel
vance with a neon lamp is recommended.
shroud screen, air intake duct and carburetor air inlet
e. Neon Lamp Timing.
hose.
CAUTION
(4) Disconnect spark plug and ignition coil wires.
Do not exceed 2200 rpm when generator-
(5) Disconnect coil and high temperatures safety
welder is hooked to the engine.
switch wires from the primary terminal.
NOTE
(6) Loosen screw on advance arm lock and remove
The engine should be timed to the 23 advanced position at
distributor assembly.
not less than 2000 rpm.
b. Cleaning and Inspection.
(1) Connect neon timing light in series with the
(1) Clean the exterior of the distributor assembly
no. 1 spark plug.
with a cloth dampened in cleaning solvent (app D).
(2) Chalk or point the end of the " X" marked vane
(2) Inspect distributor for cracks or other defects
on the flywheel.
and replace defective parts.
(3) With the engine operating at 2000 rpm or over,
(3) Remove distributor cap and inspect rotor for
allow the flash from the neon lamp to illuminate the
cracks or other defects. Inspect for burned or pitted
marked vane. At the time of the flash, the leading edge
points.
of the vane should line up with the running spark ad-
c. Installation. Install in reverse order of removal.
vance timing hole on the flywheel shroud (fig 4-4). If it
d. Distributor Timing.
does not line up, loosen the advance arm clamp screw,
(1) Remove screen over the flywheel air intake
turn the distributor body slightly clockwise or coun-
opening. This will expose the timing marks on flywheel
terclockwise, as required, until the marked flywheel
shroud and the vane on the flywheel, marked by an
vane matches up with the advance timing hole.
"X" and the letters "DC" (fig 4-4).
(4) Tighten the advance arm clamp.
WARNING
(5) Stop engine.
Operation of the engine without the
(6) Install flywheel screen.
screen in place, exposes the operator to
NOTE
A 3/8 inch diameter hole is locatcd in the screen rim to
moving flywheel vanes which can, if con-
check timing without removing screen.
tacted, cause serious injury or death.
f Distributor Point Gap Adjustment.
(2) Remove the spark plug from no. 1 cylinder and
(1) Turn engine over until the distributor breaker
turn engine over slowly, at the same time hold finger
arm rubbing block is on a high point of the cam.
over the spark plug hole to determine the compression
(2) Loosen the stationary contact screw.
stroke (para 6-12 a).
(3) Turn fixed contact screw in or out, until the
(3) Upon reaching the compression stroke, con-
