Section XI. GASOLINE ENGINE IGNITION SYSTEM
c. Installation and Timing. When the magneto has
been removed it must be retimed to the engine.
The spark is produced by a magneto. The ignition
(1) Remove the four machine screws (7, fig.
current is transmitted into the engine cylinder through an
4-39) and lift off the screen (6).
ignition cable and spark plug. A ground out cable which
connects to the shut-off switch on the engine control
(2) Remove the spark plug closest to the
panel is provided to ground out the magneto and shut
flywheel. Hold the thumb over the spark plug hole and
off the engine.
turn the engine over slowly with the hand crank until a
4-39. Spark Plugs and Wiring
definite pressure can be felt. When this occurs, the
a. Removal and Disassembly.
number one piston is coming up on the compression
stroke. Reinstall the spark plug.
(1) Remove the four coupling nuts (2, fig. 4-
401) securing the two spark plug cables (3) to the spark
plugs (1) and the magneto (6).
(2) Remove the machine screw (5), securing
the clip (4) and the spark plug cables to the cowling.
Remove the spark plug cables.
(3) Clean the dirt from around the spark
plugs. With a spark plug wrench, remove the plugs and
b. Cleaning, Inspection and Repair. Clean the
spark plugs by sand blasting. If the plugs are pitted or
burned, replace them. Replace damaged parts. Reset
plug gap to 0. 030 in. (. 0762 cm). Replace the spark
plug gaskets, if necessary.
c. Reassembly and Installation.
removal and disassembly procedures.
(1) Remove the spark plug cables and the
ground cable from the magneto.
(2) Hold a wrench on the cap screw (7, fig. 4-
401) securing the magneto (6) and remove the nut (23,
fig. 4-34) and the lock washer (22).
(3) Remove the cap screw.
(4) Hold the magneto and remove the cap
screw (24, fig. 4-34) and the internal-external lock
washer (22) securing the magneto to the timing gear
cover (21). Lift out the magneto and the gasket.
Dry cleaning solvent: P-D-680 or P-S-
661, used to clean parts is potentially
Shielded spark plug
IE toothed lock washer
dangerous to personnel and property.
Use in a well-ventilated area as the
Shielded ignition cable
fumes are dangerous if inhaled. Avoid
Timing gear cover
repeated and prolonged skin contact.
Do not use near open flame or
excessive heat. Flash point of solvent
is 100F. -138F. (38C. -59C. ).
b. Cleaning and Repair. Wipe with a clean cloth
Figure 4-40. Ignition suppression components
dampened in a cleaning solvent. Inspect the magneto
(Sheet 1 of 2)
cover for breaks or cracks. Replace all damaged parts.