Piper Comanche PA-24 Service Manual page 597

Figure 7C-12. Aligning Timing Marks
Single Contact Assembly Magneto.
3. Secure distributor block to housing with studs and washers. Tighten studs finger tight. Loosen
the 11-8465 Rotor Holding Tool and turn rotating magnet in reverse direction of rotation until
timing light indicates main contact assembly has just opened and check to make certain timing
marks align within tolerance indicated above. Tighten block securing studs, first to 4-8 inch
pounds torque and then final torque to 20 inch pounds.
4. Insert the tip of your small finger through timing hole in housing and against large distributor
gear teeth. Rock distributor gear back and forth slightly. There must be perceptible backlash
between teeth of large and small gears. This check should be made at three different points,
120° apart on gear. If backlash is not evident, replace large distributor gear.
5. Install the breaker cover and complete reassembly of the magneto. Refer to manufacturer's
publications for complete disassembly and reassembly procedures.
F. Install and time magneto, removed from engine, in accordance with paragraph 7C-53.
G. Secure external switch and retard leads to the breaker cover terminals. Connect harness assembly
to the magneto.
7C-53. Installation And Timing Procedure. (Timing Magneto to Engine.)
A. Remove a spark plug from No. 1 cylinder and turn crankshaft in direction of normal rotation until
the compression stroke is reached.
NOTE: The advance timing mark on the top face of the starter ring gear is marked at both 20° and
25° BTC. Use only the 25 ° BTC mark when timing the magnetos to the engine.
NOTE: Verify correct engine timing for the airplane being worked on by checking the engine
dataplate.
04/01/09
PIPER COMANCHE SERVICE MANUAL
2H15
Figure 7C-13. Forming Leads In
Breaker Compartment
VIIC - POWER PLANT
(PA-24-260 TURBO)