Magneto Timing Procedure (Internal Timing) - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
8-75. MAGNETO TIMING PROCEDURE (INTERNAL TIMING).
a.
Remove magneto cover and disconnect air pressure hose from magneto housing.
b.
Loosen flange clamps and remove magneto from engine.
c.
Check condition of points; replace if necessary.
d.
Rotate the magneto drive shaft until a main cam lobe touches the follower of the left main
breaker assembly and adjust the breaker points to an initial opening of .016 inch. Wire feeler gauge is
recommended.
e.
Adjust right main breaker contact assembly to an initial point opening of .016 inch just as in Step
d.
f.
Rotate the retard cam until lobe touches cam follower and check retard breaker contact for .016
inch point opening. Fixed contact support may be bent to adjust clearance. If support is bent, main breaker
contact must be rechecked. Torque breaker securing screws to 20-25 inch-pounds.
NOTE
Bend bracket carefully. Do not correct by bending back if bent
too much; this weakens the bracket.
g.
Position rotor so keyway is at 12 o'clock position and red painted distributor teeth are visible in
timing windows.
h.
Loosen drive shaft nut and position the Rotor Holding Tool (Bendix part number 11-8465)
under washer or bushing on drive end of rotor shaft with clamp at 4 o'clock position so any shaft deflection
caused by clamping action will be in a plane parallel to breaker contacts. Tighten nut to secure holding tool
to shaft. Check to insure proper location of keyway and tighten adjusting screw of holding tool to lock
rotor in position.
i.
Loosen rotor holding tool and turn magnet in direction of rotation until adjacent "R" or "L"
("E" gap) mark is aligned with pointer and lock in position. Both red painted teeth should be
approximately centered in timing windows.
NOTE
The use of the timing light unit, part number 11-9110-1 available
from Bendix will simplify the internal timing procedure and
breaker synchronization.
Reissued: 9/23/80
POWER PLANT
2122