through the lower half of the inspection hole in the
identified by an 'X' mark cast on the end. See Fig. 6.
gear cover, as shown in Timing Diagram, Fig. 6.
When the air blows out of the No. 1 spark plug hole,
Tighten the nut and capscrew for mounting the magneto
continue turning the engine until the edge of the marked
to the gear cover, making sure the magneto flange
vane on flywheel is on line with the mark on the vertical
gasket is in place.
centerline of the shroud as shown on Fig. 6. Leave
flywheel in this position. At this point the keyway for
The No. 1 terminal is identified on the magneto cap.
mounting the flywheel is also on top. Reassemble spark
The terminals follow the proper firing order of 1-3-4-2 in
a clockwise direction viewing the cap end. The leads
from the magneto should be connected to spark plugs of
Next, remove the inspection hole plug from the magneto
timing opening, located in the gear cover.
No.1 cylinder is the cylinder nearest the fan-flywheel of
Assuming that the magneto has been removed from the
the engine in the left bank and No. 3 cylinder is the
engine, the following procedure should be followed
other cylinder in that bank. No. 2 cylinder is across the
engine from No. 1 and No. 4 is across from No. 3.
The Number 1 cylinder firing position of the magneto
When the magneto is properly timed the impulse
must be determined. Insert the ignition cable into the
coupling will snap when the 'DC' and 'X' marked vane of
No. 1 tower terminal of the magneto end cap and hold
the flywheel, line up with the mark on the flywheel
the spark plug terminal at the other end, about 1/8"
shroud which indicate the centerline of the No. 1 and 3
away from the magneto body. Turn the magneto gear in
cylinders. This can be checked by turning crankshaft
a clockwise rotation, tripping the impulse coupling, until
over slowly by means of pulsing the starter. The
the No. 1 terminal sparks, then hold the gear in this
impulse will also snap every 1800 of flywheel rotation
position. Mount the magneto to the engine, meshing the
gears so that when the magneto is in place, the gear
tooth marked with an 'X' will be visible TM 5-3895-359-
FIGURE 6. MAGNETO TIMING DIAGRAM