Piper Comanche PA-24 Service Manual page 553

PIPER COMANCHE SERVICE MANUAL
7B-50_ ilupec:tion ADd Clanin, Of Sport. Plul_
._ Visually inspect eadt spark plul for the followiDs aon-repaiftbk defec:a,
L
Severely d.unq<d sheU or shield threads nicked up. Stripped or aoathreaded.
Z. Badly battered or rounded sheU """"IOns.
3. Out-of-round Ot damaged shieldinJ barrel.
4.
Chipped. encked. or broken ceramic insulator portions.
5. Badly eroded electrodes worn to &l'proximately
,oq(,
of oriJiaal size_
b. Clean the spark plu, .. required.
removing
carbon and for .... doposia.
c.
Test me spark pi", both elec:u-icalJy and for raiswlce.
d. Set the electrode
' & I'
at .015
ro .018 of
UI
iach or ii
&
smoother operation at idle speed and
reduced magneto
dro~ff
is desired.
Set
at .018
to
.022 of an iacb. However. with wide
' & I'
settins
the
plup must be serviced at more frequent iamvals. Fiae wire platinum or iridium elec:uodes should be
Set
at
.015 to .018 of an inch ollly.
7B-51. I.....u.tion Of
Spck' ... Before insalling spark plugs. ucett2in that the threads within the
cylinder are dean and not da.mo... ... cQ..
..
Apply anti...ue compound spuingly on the threw &ad install psket and spark plup. Torque 360
to
~20
inch pounds.
CAUTION
M&i<e ceruin the deep socket is properly seated on the spark pi",
hexqon .. damage to the plug could result ii the wrench
is cocked to
one side when pressure is applied.
b. CuefuUy insert the tenninal insulator in the spark plug and tilhtcn the
co~pling
nut.
7B-52. Lubrication System.
7B-53. Oil Relief Val ... The function of the oil pressure relief
valve.
which
IS
located between the upper
nght engine mounting lug &ad No.7 cylinder.
IS
to maintain engine oil pressure within specified limlt5 by
withdrawing
il
portion of the oil from the circulatina system and returning the oil to the sump should the
pressure become excessive. Tbis valve is noc adjuStable, however, panicles of metal or other forclll' matter
lodged berween ball .rid ..
at
will result in • drop in oil pressure. It is advisable. merefore. to disassemble.
inspect and clean the relicf vah'c if
excCSSlvc
pressure fluctuations are noted.
The oil pressure relief valve is by no means to be confused with the oil cooler by·pass valve. whIch
is
located on the: au. pressure screen housing mountmg pad. The sole purpose of the by·pass valve :s to serve
a.s
a safety measure. pemutnns: pressure oil to by-pass the oil cooler enarely in case of an obstTUcnon withm
the cooler
POWER PLANT
ISSUED: 8/18172
2F23