Piper Comanche PA-24 Service Manual page 507

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PIPER COMANCHE SERVICE MANUAL
7 A-SI. Inspection And Cleaning
or
Spark Plug.
a. Visually inspect each spark plug for the following non-repairable defects
I Severely damaged shell or shield threads nicked up. stripped or crossthreaded.
2 Badly battered or rounded shell hexagons
, Out-of-round or damaged shielding barrel.
4 Chipped. cracked. or broken ceramic insulator portions
5 Badly eroded electrodes worn to approximately 50S of original size
b Clean the spark plug as required. removing carbon and foreign deposits
c Test the spark plug both electrically and for resistance
d Set the electrode gap at .015 to .01S of an inch or if a smoother operation at idle speed and reduced
magneto drop-off is desired. set at .018 to 022 of an inch. However. with wide gap setting the plugs must be
serviced at more frequent intenals Fine wire platinum or iridium electrodes should be set at .015
to
.018 of
an inch only
7 A-S2 Installation
or
Spark Plugs. Before installing spark plugs. ascertain that 'he threads within the
cylinder are clean and not damaged
a Apply anti-seize compound sparingly on the threads and install gasket and spark plugs Torque ,60
to 420 inch pounds
CAUTIO~
Make cenain the deep socket is properly seated on the spark plug
hexagon as damage
to
the plug could result if the wrench is cocked to
one side when pressure is applied
b Carefully insert the terminal insulator in the spark plug and tighten the coupling nut
7 A-8J Lubrication System.
7 A-84 Oil Pressure Relief Valve. Subject engines mav be equipped with either an adjustable or non-
adjustable oil pressure relief valve A brief description of both types follows·
a. 'on-adjustable Oil Pressure Relief Valve: The ,·alve is not adjustable. however. the pressure can be
controlled by the addition of a maximum of three STD-425 washers under the cap to increase pressure or
the use of a spacer I Lycoming Pi'" 7,629 or 7J6JO)
to
decrease pressure. Particles of metal or other foreign
matter lodged between the ball and seat will result in a drop in oil pressure It is advisable. therefore
to
disassemble. inspect. and clean the valve if excessive pressure fluctuations are noted. The oil pressure relief
,ahe is not to be mistaken for the oil cooler by-pass ,alve. whose function is to permit pres,ure oil
to
oy-pass the oil cooler in case of an obstruction
b Adjustable Oil Pressure Relief Valve· The adjustable oil pressure relief valve enables the operator
to
maintain engine oil pressure within the specified limits (refer to the engine manufacturer's appropriate
manual) The ,ahe is located above and to the rear of
'0.
5
cylinder. If the pressure under normal operating
conditions should consistently exceed 90 psi. or run less than 60 psi. adjust the val,e as follows
ISSt·ED: 8/18/72
2ES
POWER PLANT