Lycoming IVO-540 Series, Operator'S Manual

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LYCOMING OPERATOR’S MANUAL SECTION 5
VO, IVO & TIVO-540 SERIES MAINTENANCE PROCEDURES
SECTION 5
MAINTENANCE PROCEDURES
The procedure 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 preceding
section.
1. IGNITION 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 fastened at the correct location.
b. Timing Magnetos to Engine – Although several combinations of magnetos are used on the subject
engines (see Table of Models for model application), the timing procedures in the following
paragraphs are the same for all magnetos. Either the impulse coupling or retard breaker magneto
(whichever is applicable) is installed on the right side of the engine.
(1) Remove the timing inspection hole plug, located on the left side of the accessory housing adjacent
to the magneto. 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 thumb off spark plug
hole. Look into timing hole and continue turning crankshaft until timing pin and timing mark on
the chamfered tooth of camshaft gear are in alignment. At this point, engine is at 25° BTC on
compression stroke of No. 1 cylinder and is ready for assembly of the magnetos.
NOTE
If the crankshaft is accidentally turned in the direction opposite normal rotation, repeat the
above procedure as accumulated backlash will make the final timing incorrect.
(2) Remove the inspection plugs from both magnetos and turn the drive shafts in direction of normal
rotation until the first painted chamfered tooth on the distributor gear is aligned in the center of the
inspection window. Being sure that the gear does not move from this position, install gaskets and
magnetos on the engine. Secure with washers and nuts; tighten only finger tight.
NOTE
In order to turn the shaft on an impulse coupling magneto, depress the pawl on the impulse
coupling with the finger.
(3) Using a battery powered timing light, attach the positive lead to a suitable terminal connected to
the ground terminal of the magneto and the negative lead to any unpainted portion of the engine.
Rotate the magneto in its mounting flange to a point where the light comes on, then slowly turn it
in the opposite direction until the light goes out. Bring the magneto back slowly until the light just
comes on and tighten nuts. Repeat this with the second magneto.
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