Spark Plugs - TM-10-3930-632-120064

TM 10-3930-632-12

WARNING

Dry cleaning solvent, P-D-680, used to

clean parts is potentially dangerous to

personnel and property. Avoid repeated

and prolonged skin contact. Do not use

near open flame or excessive heat. Flash

point of solvent is 100F. -138F. (38C. -

60C.).

c. Cleaning and Inspection.

(1) Clean the distributor with a cloth

dampened with dry cleaning solvent P-D-680; dry

thoroughly.

(2) Inspect the distributor cap and rotor for

cracks, chips, carbon runners, corroded terminals, and

burned inserts. Replace the cap and rotor if defective.

(3) Rotate the distributor shaft. It must

turn freely without excess play.

(4) Turn the breaker cam slightly in the

direction of rotation. The advance springs shall return

the cam to the original position without hesitation or

Figure 4-22. Checking Distributor Point Cap

catching. If defective, replace the distributor.

d. Installation.

(3) Check the condition of the contact

(1) Install the distributor as shown in figure

surfaces of the points. If they are rough or pitted, dress

4-21, using the sketch made during disassembly to

them using a contact point file. Remove only the worst

assure correct wire connection.

roughness. Complete smoothness of the points is not

(2) Time the distributor as directed in

necessary.

paragraph 4-64a.

(4) If the contact points are badly pitted

and burned, replace the points. If the points are good

4-35. Spark Plugs

enough for continued service, proceed to subparagraph

a. Removal. Disconnect the spark plug leads

(8).

from the spark plugs. Clean the area of the cylinder

(5) Remove the screws that secure the

head around the plugs. Use a spark plug socket wrench

contact set and capacitor to the distributor; remove the

to remove the spark plugs.

parts as shown in figure 4-21.

WARNING

(6) Install new contact set and capacitor in

Dry cleaning solvent, P-D-680, used to

the same positions from which the old ones were

clean parts is potentially dangerous to

removed.

personnel and property. Avoid repeated

(7) Using the starting motor to crank the

and prolonged skin contact. Do not use

engine, turn over the engine until the contact point cam

near open flame or excessive heat. Flash

follower is on the high point of the cam (points open as

point of solvent is 100F. -138 F. (38C. -

far as possible); refer to figure 4-22.

60C.).

(8) Use a wire feeler gage as shown in

b. Cleaning and Inspection.

figure 4-22 to check the point opening. If the point gap

(1) Clean the exterior of the spark plugs

is not 0.022 inch, loosen the lock screw with a

with a cloth dampened with dry cleaning solvent P-D-

screwdriver and position the adjusting plate of the point

680. Use a sand-blast type cleaner, if available, to

set until the correct point opening is attained. Tighten

clean the electrodes.

the lock screw.

(2) Inspect the spark plugs for cracked

(9) Install rotor and install the distributor

insulation, burned electrodes, and other damage.

cap. Make sure all spark plug leads and the ignition coil

(3) Test the spark plugs on a high-voltage

high tension leads are firmly seated in the distributor

tester. A hot, blue spark must arc across the electrodes

cap.

during the test. Replace shorted plugs.

b. Removal.

(4) If the spark plugs are suitable for

(1) Draw a sketch showing the proper

reuse, check and adjust the spark plug gap. Check the

connection of the electrical leads to the distributor.

gap on new or used plugs with a wire feeler gage

Disconnect the electrical leads.

(2) Remove the distributor as shown in

figure

4-37