Figure 5-4. Contact Gap Adjustment

to see if distributor lines up with distributor cap segment

connected to No. 1 cylinder and that the remaining ones

are connected in the firing order of 1-5-3-6-24.

5-60. DISTRIBUTOR ADJUSTMENTS.

a. Contact gap adjustment (See Figure 5-4). The

contact point opening must be set to specification.

Points set too close tend to burn and pit rapidly. Points

with excessive separation tend to cause a weak spark at

high speed. Rotate breaker cam until breaker lever

rubbing block is on the high point of the cam lobe, thus

giving the maximum point opening. Loosen the clamp

screw, holding the contact support and adjust point

opening by turning screw on contact support. Contact

opening should be 0.022 inch. Tighten clamp screw and

check with feeler gauge again. The cam angle of the

distributor is 31 deg to 37 deg.

NOTE

The contact points should be cleaned

before adjusting if they have been in

service.

b. Contact point pressure check. Contact point

Figure 5-4. Contact Gap Adjustment

pressure must fall within the limits given. Weak tension

will cause point chatter and ignition miss at high speed,

spotting the engine. When the dead center mark on the

while excessive tension will cause undue wear of contact

flywheel lines up with the mark across the center of the

points and cam. Check the contact point pressure with a

hole in the bellhousing, the pistons for No. 1 and No. 6

tension gauge calibrated to indicate ounces of pull, as

cylinder are in top dead center position.

shown in Figure 5-5. The amount of pull required to

a. The first step in setting or checking the ignition

open the gap must be between 17 to 21 ounces.

timing is to locate the dead center mark and line it up

Replace the contact support arm if it is not within these

with the mark on the bellhousing. To determine whether

limits.

the engine is in firing position for No. 1 or No. 6, the

engine can be cranked with spark plugs removed to

5-61. SPARK PLUG SERVICING.

determine the compression stroke of one of these

a. Clean spark plugs with standard spark plug

cylinders or the valve cover assembly can be removed

cleaning equipment. If the electrodes are excessively

and the position of valves noted. If both tappets for No.

burned, install new spark plugs. Tighten to 30 foot-

1 cylinder are clear, indicating that the valves are closed

pounds torque.

and exhaust on No. 6 is not completely closed, this will

b. Using a round feeler gauge, check for proper

indicate firing position for No. 1 cylinder.

gap between the spark plug electrodes. Adjust the gap

b. To check accurately the exact point of contact

to 0.030 inch by bending the side electrode only.

opening, use a test light. Connect the test light in series

with primary circuit (when ignition switch is on). The test

light will be lighted when ignition contacts are closed and

not lighted when contacts are open.

c. To change ignition timing, loosen screw holding

advance arm to distributor and turn distributor until

correct timing is obtained and then tighten screw.

Clockwise rotation will advance spark and counter-

clockwise rotation will retard it. If distributor is being

retimed after having been removed, it is necessary

Figure 5-5. Contact Point Pressure Check