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10-66
IGNITION SYSTEM
ELECTRICAL SYSTEMS
(342)
"
AIR BLAST
@Cl
EA N IN G
BLAST
3. Place spark plug in adapter of proper
size and hold adapter and plug in spark plug
cleaner with one hand. Push cleaner hood half
way down to "air-blast" position to blowout
loose dirt and dry out
plug,
then press hood all
the way down to "cleaning-blast" position and
hold for 2 or 3
seconds.
See figure 10-81.
4. Release hood to half way or "air-blast"
position, hold several seconds to blowout clean-
Figure 1O-SI -Use of AC Spark Plug Cleaner
plug which has a cracked or broken insulator,
or which has loose
electrodes.
If the insulator
is worn away around the center electrode, or
the electrodes are burned or worn so they can-
not be adjusted for proper gap, a spark plug is
worn out and should be discarded. Spark plugs
which are in good condition except for carbon
or oxide deposits should be thoroughly cleaned
and adjusted.
b. Spark Plug Cleaning
Spark plugs which have carbon or oxide de-
posits should be cleaned in a blast t
ype
spark
plug cleaner. Scraping with a pointed tool will
not properly remove the deposits and may dam-
age the insulator. The following procedure cov-
ers u'se of the AC spark plug cleaner
;
however,
the same principles apply to the use of
any
blast type cleaner.
1.
If
spark plugs have a wet or oily deposit
dip them in a degreasing solvent and then dry
thoroughly with dry compressed
air.
Oily plugs
will cause the cleaning compound to pack in
the shell.
2. Make sure that cleaner nozzle is not
worn excessively;
otherwise, t
he cleaning com-
pound will not be properly directed into the
shell.
THIS
KIND
OF
BREAKAGE CAN
NEVER BE CAUSED
BY THE ENGINE
Figure 10-S0-Broken Spark Plug tnsulators
a. Removal and Inspection
1. Use
a
1%6"
so-ket
wrench to remove all
spark
plug s.
An oversized or worn wrench may
distort
the spark plug shell and crack the in-
sulator.
If socket wr ench is allowed to press
against the outer end of plug, the insulator will
be cracked or
broken.
See figure 10-80.
2. Carefully
inspect the insulators and elec-
trodes of all spark plugs. Replace any spark
II
I
. ..
:
the yellow band of ignition timing mark and as
near leading edge of band as possible. This is
proper position to
fire
number one
cylinder.
l
3. Loosen
distributor
attaching bolts just
enough so that distributor housing can be
turned in
crankcase.
4. Turn on
ignition.
Remove the center
high tension lead from distributor cap and hold
end in position to form a gap with distributor
housing.
Make sure that contact points are
closed, then slowly move distributor housing in
a
clockwise
direction until points just open and
a spark is produced at the gap. See figure 10-79.
Tighten distributor attaching bolts.
5. Check timing setting by turning engine
over two complete revolutions and until a spark
is produced at gap between high tension lead
and housing when distributor rotor is under
No.1 ignition cable terminal in cap. The index
mark must fall
within
the yellow band of igni-
tion timing mark on
flywheel.
6. Install
timing
hole cover.
10-48 SPARK PLUG CLEANING AND
ADJUSTMENT
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