8-30. INSTALLATION AND TIMING PROCEDURE. (Timing Magneto to Engine) (4200 series magnetos.)
The magnetos can be installed and timed to the engine by the following procedure:
—WARNING—
Be sure switch is in "OFF" position and the "P" lead is grounded.
a. Remove the top spark plug from the number one cylinder. Place a thumb over the spark plug hole and turn
the engine crankshaft in the normal direction of rotation until the compression stroke is reached. The
compression stroke is indicated by positive pressure inside the cylinder tending to lift the thumb off the spark
plug hole. In this position both valves of the number one cylinder are closed. Turn the crankshaft opposite to its
normal direction of rotation until it is approximately 35 degrees BTC on the compression stroke of number one
cylinder. Rotate the crankshaft in its normal direction of rotation until the 25 degree mark on the starter ring gear
and hole in the starter housing align.
the rotation of magneto until the pin engages the gear and install magneto and gasket on the mounting pad of the
accessory housing and remove the timing pin. Tighten the bolts finger tight.
c. Connect a standard timing light between engine ground and the left magneto condenser-terminal. Switch
must be"ON".
d. Rotate the complete magneto opposite normal rotation of the magneto on the engine mounting until the
timing light indicates the contact breaker points are just opening. Secure the magneto in this position. Turn
switch "OFF".
e. Turn on the switch of the timing light. Turn the crankshaft very slowly in the direction of normal rotation
until the timing mark on the front face of the starter ring gear aligns with the drilled hole in the starter housing, at
which point the light should come on, (on battery operated models). If not, turn the magneto in its mounting
flange slots and repeat the procedure until the light goes on at 25 degrees before top dead center. Tighten the two
mounting bolts.
f. Connect the other positive wire of the timing light to the right magneto condenser terminal and time the
magneto in the same manner as described for the left magneto.
g. After both magnetos have been timed, leave the timing light wires connected and recheck the magneto
timing as previously described to make sure both magnetos are set to fire together. If timing is correct, both
timing lights will come on simultaneously when the 25 degree mark on the ring gear aligns with the drilled hole
in the starter housing. If the points open early, loosen the mounting bolts and rotate the magneto
counterclockwise. Secure the bolts and remove the timing lights.
THIS SPACE INTENTIONALLY LEFT BLANK
PIPER AIRCRAFT
PA-28-161 CADET
AIRPLANE MAINTENANCE MANUAL
Issued: FEBRUARY. 28, 1989
POWER PLANT
1K3
