Piper Comanche PA-24 Service Manual page 503

PIPER COMANCHE SERVICE MANUAL
J. Tum the cnnksh&ft very slowly in direction of normal rotation until the riming mark on the front
face of the
liIIs
gear
~
with the drilled bole in the
starter
or the
timinJ
mark on the back of the ring
gear dilDs with the crankcase parting surfaces. At this point the !isht sbollld
,0
out.
k.
If the lisht does not go out at this point. align timmg marks and rotate magnetO on mounting
t1an,.
in the desired direCtIon and repeat the procedure una! the !isht goes OUt at .25 degrees before tOP
dead center.
CAUTION
When timing rewd breaker magnetos to the engine, only main breaker
points are timed. Never artempt
to
rime retard breaker points to the
engine.
l. Tichten the two mounnr 'un and replace the inspection plug.
m. After tia:htening macnetc. .nountint nuu. check timlng
to
mak.e sure it is still correa.
n. Install the other magnetO and rime using the preoeding instructions A throulh M.
o. With both magnetos tUned to the engine and seoured, check that they fire together. Route the
c:ranksh&ft opposite normal rotanon to approximately 3S degrees BTC with No. 1 cylinder on the
compression stroke.
p. If the magnetOS are nmed correetly, both riming lishts
will
go OUt simllluneously when the
crankshaft is turned in the normal direotion aligning the 25 d ..... !DIrks witb the drilled hole in the starter
housing or the c:rankase parting ,urfaoes.
q. DISC:onneCt timing light. Ascertain that the inspection pilii' arul breaker cover are installed and
secure.
r. Inru.ll harness plate and secure with ",",ws.
s. Connect "P" leads and safety.
t.
Connect starting vibrator lead to the Left ·200 mqnetos.
u. Secure engine cowling
7A·H Startinl Vibrator Cheokinl Procedure.
a. Measure voltage between vibrator terminal marked "in" and the ground teml.lnal while operating
starter. Ou.tput must be
a.t
l~t
8·yoLts on l2·yoLt systems.
b If voltage
is
adequate. listen for buzzing of vibrator during starting. If no buzzing is heard. eltner
the vibrator is defective or the circuit from the output "BO" terminal on the vibruor to the retard (dual
breaker) magneto is open. Check both switch and retara circuiu. Also check for good elecmcal ground.
c. Retard pOintS may not be closmg due to
""TOng
adjusancnt. or may not be clccmcaUy connected
in the CU'CUlt due to a poor connection. Inspect rewd points to sec if they close. Check for ?roper contact
at
the SWitch md retard terminals of rcurd (dual breaker) mqneto. and at the vibrator. Check Wiring.
d. Turn cngtnc in proper direction of rotation until retard points just open on So. one cylinder
position. Remove input connection from starter to prevent engine turning. Hold
~o.
one plug head 5/16
Inch irom ground; energize \-ibrator by rumlng switch to
start.
Plug lea.d should throw a
S/16
Inch spark
Obscrve spark
iilt
plugs spuk cap. If spark is weak or missing.
try
new vibrator. If this docs not correct
tfouble. remove magneto and check for Improper internal timing or improperly meshed dIStributor gC3.cs.
2
El
POWER PLANT
ISSUED: 8118/72