Magneto Installation And Timing Procedure - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
e.
With the cover and harness separated from the magneto housing, check contact assemblies to see
that cam follower is securely riveted to its spring.
f. Examine the contact points for excessive wear or burning. Figure 8-13 shows how the average contact
point will look when surfaces are separated for inspection.
CAUTION
Do not open point contacts more than .0625 of an inch for
examination of contact surfaces. Excessive spreading of the
breaker points will over stress and damage the contact spring.
Desired contact surfaces have a dull gray, sand-blasted (almost rough) or frosted appearance, over the
area where electrical contact is made. This means that points are worn in and mated to each other. thereby
providing the best possible electrical contact and highest efficiency of performance. Minor irregularities or
roughness of point surfaces are not harmful. (Refer to Figure 8-13, center.) Neither are small pits or mounds, if
not too pronounced. If there is a possibility of pit becoming deep enough to penetrate pad. (Refer to Figure 8-
13. right). reject contact assembly.
NOTE
No attempt should be made to stone or dress contact points.
Should contact assembly have bad points or show excessive wear,
the complete contact assembly should be replaced.
g.
Check condition of cam follower felts for proper lubrication. If oil has migrated from one
follower felt to another, it may be necessary to remove the lubrication from one felt strip while oiling
another. If felt is over lubricated, remove oil by using a clean, lintless cloth. If dry, apply one or two drops
of Bendix Breaker Felt Lubricant 10-86527.
h.
Check the capacitors for looseness in the magneto cover of the harness assembly and for any
physical damage. Using a Bendix 11-1767-1, -2 or -3 condenser tester or equivalent, check capacitors for
capacitance, series resistance and leakage. Capacitance shall be 0.34 to 0.41 microfarads.
i.
Check magneto to engine timing per instructions given in paragraph 8-74.
8-74. MAGNETO INSTALLATION AND TIMING PROCEDURE.
(Timing Magneto to Engine.)
WARNING
Do not attach harness spark plug ends to the spark plugs until all
magneto to engine timing procedures and magneto to switch
connections are entirely completed.
NOTE
The use of a timing light unit Part No. 11-9110 or 11-9110-1 will
simplify the timing procedure. This unit is available from the
Bendix Corporation at Sidney, New York 13838.
a.
Remove the spark plug from the No. I cylinder and turn the crankshaft in the direction of
normal rotation (for the particular engine being serviced) until the compression stroke is reached.
b. Continue turning the crankshaft until the 20
°
advance timing mark is in alignment with the small hole
located on the top face of the starter housing at the two o'clock position. (Refer to Figure 8-14.)
Reissued: 9/23/80
POWER PLANT
2115