Piper Comanche PA-24 Service Manual page 442

PIPER COMANCHE SERVICE MANUAL
7-48. Installation Of Harness. Before installing harness on magneto. check mating surfaces for cleanliness.
Spray entire face of grommet with a light coat of Plastic Mold Spray, SM-O-O-TH Silicone Spray or
equivalent. This will prevent harness grommet from sticking
to
magneto distributor block.
a. Place the harness terminal plate on the magneto and tighten nuts around the plate alternately to
seat cover squarely on magneto. Torque screws to 18 to 22 inch pounds.
b. Route ignition wires to their respective cylinders.
c. Clamp the harness assembly in position and replace the engine baffle plate.
d. Connect the leads
to
the spark plugs.
7-49. Spark Plugs.
7-50. Removal Of Spark Plugs.
a. Loosen the coupling nut on the harness lead and remove the terminal insulator from the spark plug
barrel well.
NOTE
When withdrawing the ignition cable lead connection from the plug,
care must be taken to pull the lead straight out and in line with the
center line of the plug barrel: otherwise. a side load will be applied
which frequently results in damage to the barrel insulator and
connector.
If
the lead cannot be removed easily in this manner. the
resisting contact between the neoprene collar and the barrel
insulator will be broken by a rotary twisting of the collar. Avoid
undue distortion of the collar and possible side loading of the
barrel insulator.
b. Remove the spark plug from the engine. In the course of engine operation, carbon and other
combustion products will be deposited on the end of the spark plug and will penetrate the lower threads to
some degree. As a result, greater torque is frequently required for removing a plug than for its installation.
Accordingly, the torque limitations given do not apply to plug removal and sufficient torque must be used
to unscrew the plug. The higher torque in removal is not as detrimental as in installation, since it cannot
stretch the threaded section. It does, however. impose a shearing load on this section and may, ifsufficiently
severe. produce a failure in this location. .
NOTE
Torque indicating handle should not be used for spark plug removal
because of the greater torque requirement.
c. Place spark plugs in a tray that will identify their position in the engineassoon as they are removed.
ISSUED: 8/18/72
2B16
POWER PLANT