TOPIC 5. DISTRIBUTOR (TYPE II)

TM 10-3930-644-14&P

TOPIC 5. DISTRIBUTOR (TYPE II)

GASOLINE AND L.P.G. ENGINES ONLY

B. DISTRIBUTOR SERVICE

A. DESCRIPTION

The distributor cap should be removal at regular

intervals to examine the contact points, the rotor and

The distributor is mounted on the cylinder head and is

cap. (Dust cover, located under cap, must be removed

driven off the engine lubricating oil pump extension at

before contact points can be inspected.)

one-half the engine crankshaft speed.

Check the high tension wiring for defective insulation

The distributor consists of a cast housing into which a

and poor connections at the distributor cap and spark

shaft and weight base are fitted in a bronze bushing.

plugs. Wipe the distributor cap and check the cap and

Centrifugal advance weights are pivoted on studs in the

rotor for cracks or carbon tracks indicating leakage of

weight base and are free to move against the calibrated

nigh voltage current across the surface.

weight springs which connect them to the advance cam

and breaker cam assembly. The advance cam and

Check the centrifugal advance mechanism by turning the

breaker cam assembly is slit-fitted to the too of the shaft

breaker cam in the direction of rotation and then

and rotates with the shaft, being actuated by the

releasing it The advance springs should return the cam

advance weights. Lateral movement of the weights

to its original position without sticking.

advances the cam assembly in relation to the shaft as

the speed is increased. The greater the engine speed,

Inspect the contact points. If points are badly pitted or

the farther out the distributor weights move, which

burned, they must be replaced as follows:

increases the shift in the breaker cam position and in

turn, advances the spark.

1. After distributor cap, rotor and dust cover have

been removed from distributor housing, remove

When the cam breaker is rotated by the centrifugal

the nut and washer from the inner end of the

advance mechanism, each cam lobe passes under the

primary terminal.

breaker lever rubbing block, separating the contact

points and producing a nigh voltage surge in the ignition

2. Remove the slotted head slotted head locking

circuit. With every breaker cam revolution, one spark

screw attaching the contact support to the

will be produced for each engine cylinder. Since each

distributor breaker plate, and remove the contact

cylinder fires every other revolution in a four stroke cycle

points. If condenser is to be replaced, remove

engine, the distributor is required to rotate at only one

screw attaching condenser to breaker plate and

half the engine crankshaft speed to furnish ignition.

remove and discard condenser.

Built-in distributor lubrication is mace possible with the

3. Install the replacement condenser. Apply a light

use of a porous Pushing, which extends from the upper

coat of high quality silicone grease to breaker

to the lower part o the housing. A well is provided which

cam.

Install the new contact support with

is kept filled with oil. Seepage through the porous

breaker lever over the pivot post. Install the

bushing provides shaft lubrication.

slotted head locking screw which attaches

contact support to breaker plate but do not fully

A dust cover located under the distributor cap completely

tighten screw as yet. Connect the primary lead

seals off the breaker compartment from dust or dirt.

to breaker plate.

The high tension terminals on the ignition coil and the

NOTE

distributor cap are covered with tight fitting neoprene

Make certain proper installation is

nipples to prevent moisture and dust accumulation,

made and all connections are tight.

thereby preventing a conductive path to ground which

would cause the engine to misfire.

4. Rotate crankshaft until the breaker lever rubbing

block is on a high spot on the cam, thus opening the

contact points to their maximum open position. Insert a

NOTE

screwdriver into the adjusting slot (Fig. 5-1) and turn

Refer to ENGINE MAINTENANCE

clockwise or counterclockwise until the specified point

MANUAL, ENGINE TUNE-UP, for

gap of .020" is obtained. Lock points in this position by

specific distributor characteristics

tightening

and

distributor-to-engine

timing

procedure.

3-98