Piper COMANCHE PA-24-180 Service Manual page 324

1. Tighten the two mounting nuts and replace he inspecion plug.
m. After tightening magneto mounting nun check timing o make sure it i still correc.
n. Insll the other magneto and time using the preceding insucrions A through M.
o. With both magnetos timed to the engine and secured, check thac they fire together. Route the
crankshaf opposite normal roution to approxinucely 35 degrees BTC with No. 1 cylinder on the
compression sroke.
p. If the magnetos are tmed correctly, both timing lights will go out simultaneously when the
crankshaft is urned in the normal direcion aligning the 25 degree marks with the drilled hole in the tarter
housing or the crnkcase pang surfaces.
q. Disconnec timing light. Ascertain that the inspection plugs and breaker cover re installed and
secure.
r. Insll harness plate and secure with screws.
s. Connect "P" lead and safey.
c. Connect sarting vibrator lead to the left -200 magneto.
u. Secure engine cowling.
7-45. Staring Vibrator Checking Procedure.
. Measure voltage between vibrator terminal marked "in" and the ground terminal while operating
starter. Output must be at least 8 volts on 12 volt systems.
b. If voltage is adequate, lisen for buzzing of vibrator during sarung. If no buzzng is heard, either
the vibrator is defective or the circuit from the output "BO" terminal on the vibrator to the retard (dual
breaker) magneto is open. Check both switch and retard circuits. Also check for good elecrical ground.
c. Retard points my not be closing due to wrong adjustment. or may be electrcally connected m
the circuit due to a poor connection. Inspect retard points to see if they close. Check for proper contact a
the switch and retard terminals of retard (dual breaker) magneto and at the vibrator. Check wiring.
d. Turn engine in proper direction of rotation until retard points just open No. 1 cylinder position.
Remove input connection from starter o prevent engine turning. On the PA-24-180, PA-24-250 snd
PA-24-260 hold No. I plug lead 5/16 inch spark. On the PA-24-400 check spark by removing spark plug,
connecting lead to plug and grounding plug. Observe spark it plugs spark cap. If spark is weak or missing
try new vibrator. If this does nor correct trouble remove magneto and check for improper internal iming or
improperly meshed distributor gears.
CAUTION
When checking vibrator acion. stand cier of propeller or remove spark
plug termunals.
POWER PLANT
ISSUED: 8/18/72
2 B14
PIPER COMANCHE SERVICE MANUAL