Piper Navajo Chieftain PA-31-350 Service Manual page 486

NAVAJO CHIEFTAIN SERVICE MANUAL
j. Connect the timing light black lead to any unpainted surface of the magneto.
k. Connect the red timing light lead to the left breaker terminal and the green lead to the right main
breaker terminal. (Refer to Figure 8-22.)
1.
Loosen rotor holding tool and move the rotor back a few degrees; then move it forward. Both
lights should go out to indicate opening of the main breakers when the timing pointer is indicating within
the width of the "L" or "R" mark and the red painted teeth are centered in timing windows.
m. If breaker timing is not correct, loosen cam securing screw (refer to Figure 8-19) and remove retard
cam; then unseat main breaker cam from taper. Using 11-3031 Retaining Ring Pliers inserted in holes in cam,
rotate main breaker cam in direction of rotation until left main breaker points just open and press cam onto
taper. Install retard cam washer and screw. Tighten screw to seat main breaker cam.
n.
Loosen rotor holding tool to turn rotating magnet back a few degrees; then turn rotating magnet
in normal direction of rotation. Timing light should go out when timing pointer is aligned with "R" or "L"
("E" gap) mark. Lock rotating magnet in position where points just open.
o.
Loosen right main breaker securing screws and position breaker so cam follower is pressed against
cam with points closed. Tighten contact assembly securing screws to prevent contact assembly from
bouncing back when moved. Using a small mallet and drift, tap right breaker in until points just open.
p.
Turn rotating magnet back a few degrees; then turn rotating magnet in normal direction of
rotation. Both timing lights should go out within one degree or half the width of "R" or "L" mark on
rotor. If breakers are not properly synchronized, reset right breaker.
q.
Check right main breaker contact for 0.016 + .004 inch point opening and torque right breaker
contact securing screws to 20-25 inch-pounds. If point opening is out of limits, repeat timing procedure
setting left main breaker opening at .016 ± .002 inch. If right contacts open beyond .020 inch, set left
contacts closer to .018 inch. If right contacts open less than .012 inch, set left contacts closer to .014 inch.
r.
Connect the 11-9110-1 timing lights to retard terminal on left contact assembly. Turn rotating
magnet in normal direction of rotation to retard angle of 11 degrees and lock in position. Carefully loosen
cam securing screw enough to allow retard cam to turn. Turn cam in normal direction of rotation until
retard breaker points just open. Torque cam securing screw 16-20 inch-pounds.
s.
Using timing light, recheck timing to insure main breakers open within one-half the width of "R"
or "L" mark and that retard breaker opens at correct degree setting. Using a wire feeler gauge, check left
main breaker for .016 + .002 inch point opening and right main breaker and retard breaker for .016 + .004
inch point opening.
NOTE
If correct breaker timing cannot be achieved, remove magneto and
have it overhauled.
t.
Check capacitors for looseness in the magneto cover of the harness assembly and for any physical
damage. The capacitors should be checked for capacitance, series resistance and leakage. Capacitance should
be 0.34 to 0.41 microfarads. The use of a Bendix condenser tester, part number 11-1767-1, -2 or -3 or
equivalent will simplify this test. Replace defective capacitors and torque securing nut to 60-70
inch-pounds.
NOTE
Spring in capacitor outlet may cause an indication of a short to
ground if adapter lead is not used. (Refer to paragraph 8-74, Step c,
Note.)
Revised: 9/24/81
POWER PLANT
2123