Ignition And Electrical System; Ignition Harness And Wire Replacement; Timing Magnetos To Engine - Lycoming O-320 76 Series Operator's Manual

LYCOMING SERIES OPERATOR'S MANUAL
O-320
The procedures described in this section are provided to guide and instruct personnel in performing such
maintenance operations that may be required in conjunction with the periodic inspections listed in the
preceding section. No attempt is made to include repair and replacement operations that will be found in the
applicable Lycoming Overhaul Manual.

1. IGNITION AND ELECTRICAL SYSTEM.

a. Ignition Harness and Wire Replacement – In the event that an ignition harness or an individual lead is
to be replaced, consult the wiring diagram to be sure harness is correctly installed. Mark location of
clamps and clips to be certain the replacement is clamped at correct locations.
b. Timing Magnetos to Engine –
(1) Remove a spark plug from No. 1 cylinder and place a thumb over the spark plug hole. Rotate the
crankshaft in direction of normal rotation until the compression stroke is reached, this is indicated
by a positive pressure inside the cylinder tending to push the thumb off the spark plug hole.
Continue rotating the crankshaft until the advance timing mark on the front face of the starter ring
gear is in alignment with the small hole located at the two o'clock position on the front face of the
starter housing. (Ring gear may be marked at 20° and 25°. Consult specifications for correct
timing mark for your installation.) At this point, the engine is ready for assembly of the magneto.
c. Dual Magneto –
(1) Place the engine in the No. 1 firing position as directed in paragraph 1.b.(1).
(2) Install the magneto-to-engine gasket on the magneto flange.
DO NOT ATTACH HARNESS SPARK PLUG ENDS TO THE SPARK PLUGS UNTIL ALL
MAGNETO-TO-ENGINE
CONNECTIONS ARE ENTIRELY COMPLETED.
(3) Remove engine-to-magneto drive gear train backlash by turning engine magneto drive in direction
opposite to normal rotation and return to timing mark on the starter support in direction of normal
rotation.
(4) Remove the timing window plug from the most convenient side of the magneto housing and the
plug from the rotor viewing location in the center of the housing.
(5) Turn the rotating magnet drive shaft in the normal direction of magneto rotation until the painted
tooth of the large distributor gear is centered in the timing hole.
SECTION 5
MAINTENANCE PROCEDURES
WARNING
TIMING PROCEDURES
MAINTENANCE PROCEDURES
AND MAGNETO-TO-SWITCH
SECTION 5
5-1