Piper Comanche PA-24 Service Manual page 439

PIPER COMANCHE SERVICE MANUAL
c. Rotate the drive ,ear on the .....,.etO until the chamfered tooth on the distributor ,ear inside the
magneto llien- with the white pointer as .. en through the inspection hole in the magn .. o bousing.
d. Without allowinl tbe gear to tum from this position. insuIl the .....,. ..
0
with
guIt. ..
on the engine
and secure with washen ~d nuts.
e. TiJbten nuts sufficiently to bold mapeto in position and yet allow it to be rotated.
f. Futen the ground lead of the timing light to an unpainted metalli<: portion of the magn .. o and
one pOSlcve lead to the terminal side of the main breaker POinD.
I.
Tum on tbe timing IiJht switch.
h. Rotate the magn .. o bousing in the direction of the .....,. .. rotation a few deg:-ees until the timing
light comes on. Then slowly tum the .....,.eto in opposite direction until the timiDtlliJht jUst goes OUt.
Secure the magn .. o housing in thIS position.
NOTE
Some nming IiJhts operate the opposite of the one mentioned.
I.
Rotate the crankshaft opposite normal rotation until it is
appro~imate\y
3S degrees BTC on
compression stroke No. one cylinder.
NOTE
The crankshaft should not be rotated more than 10 degrees in direction
oppoSIte nonnal rotation from the 2S degree BTC as the pawl on the
impulse coupling (·21 magnetos) will engage with the stOp pin and I .. e
timing will be indicated through the impulse coupling mechanism. If tbis
should happen. rotate cranksh&it '" nOnnal direction until sharp click is
heard, this will indic .. e that the impulse coupling has pUKd through
fll'ing position. Tum crankshilft in dirccnon opposite nonnal
rotatIon [0
approximately 3S degrees BTC and proceed with
wn~
check.
j.
Tum the
a"1nksh.ait
very slowly in dl!'ection of nonnal rotation until the timing mark on the fronc
face of the ring gear
aIiJns
with the dnlled hole in the Starter or the timing mark on the b.ck of the nng
,eu lliens with the crankcase parting surfaces. At this point the IiJht sbould go out.
k. If
the
light does not go
OUt i t
this point. align
timins
marks and rotate magneto on mounting
flange in the desired direcnon and repeat the procedure until the IiJht go .. OUt
at
25 degre .. before tOP
dead center.
CAUTION
When tuning retard breaker magnnos to the englne. only main bteaker
pointS are timed. Sever attempt to time rewd breaker porntS to the
engine.
2 813
POWER PLANT
ISSUED: 8/18172