Piper Comanche PA-24 Service Manual page 541

PIPER COMANCHE SERVICE MANLAL
The idle mixture must be adjusted with the fuel boost pump
"0' ..
d When the idling speed has been stabili7ed. mo\e the cockpit mixture control with a smooth. stead\
pull IOward the "Idle Cut-Off" position and ob,er\e the tachometer for an~ change during the "leaning:'
proce" Caution must be exercised to return the mixture control to the "Full Rich" position before the RPM
ca
11
drop to a point \\ here the engine cuts out. An increase of more than 50 RPM \\ hile-'Iea ning out" indica te<
an
exce"i\el~
rich idle mixture An immediate decrea,e in RPM (il not preceded b\ a momenta" increase)
indicates the idle mi,ture is
100
lean
e If the abo\e indicate, that the idle adjustment is too rich or
100
lean. turn the idle mIXture adjust-
ment in the direction required for correction. a~d check this new position b\' repeating the abo\e procedure
Make additional adjustments as necessary. Each time the adjustment is changed. the engine should be run up
to 2000 RPM to ckar the engine bdore proceeding with the RPM check Make final adjustment of the idk
'peed adjustment
10
ohtain the desired idling R PM with closed thronle The abo\e method alms at a ,,·tling
that will obtain ma,imum RPM \\ith minimum manifold pre"ure In case the sening does not remain stable.
check the idle linkage.
an~
looseness in this linkage would cause erratic idling In all cases. allowance ,hould
be made lor the dlect of \\eather conditions and field altitude upon idling adju'tment.
78-:1:1 Fuel Air Bleed ,,"allIes.
78-:14 Removal
or
Fuel Air Bleed Nozzles. (Reier
10
Figure 78-7) The nOl7les must be carefull~
remmed
as
the~
or the
c~linde" ma~
be damaged
a 1
ift
the side acces" panels 01 the engine co\\ling.
b Disconnect the fuel line from the n077le
c
d
Carcfull~
remo\e the nOllle. uSing the correct sile
d~t:"r
'iocket
Clean and impect the nOllk as gi\en in Paragraph 7B-:15
7B-:15 Cleaning And Inspection
or
Fuel Air Bleed 1'00zzles.
a Clean the n077le, \\ ith acelOne or Met hslet hdketone (M E K) and blowout a II foreign pa rliel" wit h
compre"ed air in the direction oppo,ite that of fuel flo\\ Do not me wire or other hard nbjech
!()
clean
orifice..;
b Inspect the n077le and cslinder threads for nicks. ,tripping or cro"-threadml' and ballered or
rou nded he xagons.
c Inspect and replace n077le a-rings lound to be cracked. brillie or distorted Reier to L\coming
Ser\ice Instructions '0 1275 for detaded teq procedure of air bleed n077les
7B-:1(' Installation
or
Fuel Air Bleed "'Ollie.
a It is important for the n077I" to be correctl\ positioned with the air bleed hole facing up\\ard
h
Install the nonie, and tighten to a lillie lO's than (,0 inch-pounds torljue
c
Continue to tighten the n077les until the leller or number stamped on the hex of the
nOl1ie
bod\
points down In this posilion the air bleed hole \\illiace up\\ard
ISSl"EO: 8/18/72
2Fll
POWER PI...\"T