Piper PA-24 Comanche Service Manual page 468

PIPER COMANCHE SERVICE MANt:Al
Timing Mark
FIGt'RE 7C-14. ENGINE TIMING MARKS
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FIGURE 7C..IS. MAGNETO TIMISG
~ARKS
b. Continue turning the crankshaft until the 25° advance timing mark is in alignment with the small
hole located on the top face of the starter housing at the two
0
'clock position. (Refer to Figure 7C-14.)
c. Remove the inspection plug on the left magneto and turn the drive coupling in direction of normal
rotation until the first painted chamfered tooth is aligned in the center of the inspection hole. (Refer.
Figure 7C-15.) Without allowing the gear to turn from this position. assemble gasket and magneto to
engine. Secure in place with washers and nuts; tighten only finger tight.
d. Fasten ground wire of electric timing light to any unpainted portion of the engine. and one of the
positive wires of the timing light to a suitable terminal connected to the ground terminal of the magneto.
Then turn the engine crankshaft several degrees from the advance timing mark in direction opposite to that
of normal rotation.
e. Turn on the switch of the timing light. which should be lit. Turn the crankshaft slowly in direction
of normal rotation until the mark on the starter gear aligns with the hole in the starter housing. at which
point the light should go out.
If
not. turn the magneto in its mounting flange and repeat the procedure until
the light goes out. Repeat the same procedures with the right magneto.
~OTE
Battery powered timing lights operate in the reverse manner from
that described above; the light goes on when the marks align.
f.
After both magnetos have been timed. leave the timing light wires connected and recheck
magnetos as previously described to make sure that both magnetos are set to fire together. If timing is
correct. both timing lights will go out simultaneously when the timing marks are in alignment. Tighten nuts
to specified torque,
REVISED: ../10/81
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POWER
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