Magneto Removal; Timing Procedure (Internal Timing) - Piper PA-24 Comanche Service Manual

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PIPER COMANCHE SERVICE MANUAL
~FT ~CTATION
MEASURE BODY
THICKNESS HERE
FIGURE 7-9. LEAD POSITIONING
FIGURE
7..tO.
IMPULSE COUPLING
Remove the harness outlet plate from the magneto by removing the four attaching screws.
Remove the two nuts and washers securing the magneto to the engine accessory housing.
Pull the magneto from the engine.
e.
7-41. Removal Of Magneto.
a. lift the side panels of the engine cowling.
b. Disconnect the "P" lead from the magneto and the retard breaker lead from the left. -200 series.
magneto.
c.
d.
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7.42. Timing Procedure. (Internal Timing) -20 and
-200
series magneto main breaker points. When
installing new or adjusting breaker points and before timing the magneto the engine. it is important that the
internal timing of the magneto be correct.
a. To internally time the magneto it should be removed from the engine to determine
"EO<
gap.
b.
To determine
"E"
gap. find neutral position of the magneto drive
by
rotating drive coupling in a
left hand direction until the red or white chamfered tooth on the distributor drive gear appears through the
timing inspection hole. At the same location. the drive should feel to have fallen into a notch or neutral
position.
c. Rotate coupling from neutral. in a left hand direction
100.
appearing through timing hole. when
the white or red tooth aligns with the white line of the distributor block. the magneto is set at
"EO<
gap. (Refer
to Figure 7-11.) Alignment may not vary over +4°.
d. Using the alignment of the chamfered tooth on the distributor gear and the white line of the
distributor
block as a reference. adjust the breaker points to open at this point. Turn the magneto drive
until the cam follower is on high point of the cam lobe. Measure contact clearance. it must be .018 inch + .006
with the point opening set at "E" gap + 4°.
If
breaker points do not come within tolera.nees. they should be replaced.
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ISSl'ED: 8/18/72
2B9
POWER
PLANT