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20-6
GROUP 20- MAINTENANCE OPERATIONS
CLEANING AND INSPECTION
1. Examine the firing ends of the
spark
plugs, noting the type of de-
posits· and the degree of electrode
erosion. Refer to Fig. 6
for
the
various types
of spark plug con-
ditions and causes.
2. Clean the plugs on a sand blast
cleaner, following the manufacturer's
instructions. Do not prolong the
use of the abrasive blast as it
will erode the insulator. Remove
carbon
and
other deposits from the
threads
with a stiff
wire brush. Any
deposits will
retard
the heat flow from
the plug to the cylinder head causing
spark plug
overheating and pre-
ignition.
3. Clean the electrode surfaces
with a small file (Fig. 7). Dress
the electrodes to secure flat
parallel surfaces on both the
centre and side electrode.
4.
Mter cleaning, examine
the plug
carefully
for
cracked
or broken insu-
lators, badly pitted
electrodes,
and
other signs
of failure. Replace as
required.
ADJUSTMENT
Set
the spark
plug gap by bending
the
ground
electrode
(Fig.
8).
Never bend the centre electrode.
TESTING
After the proper gap is obtained,
check the
plugs on a testing machine.
Compare
the
sparking
efficiency of
the cleaned
and
gapped plug with a
new plug. Replace the plug if it fails
to
pass the test
as
outlined in the
tester
instruction
manual.
Test the plugs for compression
leakage at the insulator
seal.
Apply a
coating
of oil to the
shoulder
of the
plug where the insulator projects
through the
shell,
and to the top of
the plug,
where
the centre electrode
and terminal project from the insula-
tor. Place the
spark
plug under pres-
sure with
the tester's high tension
wire removed from
the spark
plug.
Leakage is indicated by air bubbling
through the
oil.
If the test indicates
compression
leakage, replace the
plug.
If
the
plug is satisfactory,
wipe
it
clean.
INSTALLATION
1. Install the
spark
plugs and
torque
each
plug to 15-20 ft-lbs.
2. Connect the
spark
plug wires.
Check
wire
position in
support
brackets. Press wires firmly into
proper bracket
slots.
Push all weather
seals into
position.
FIG. 7- Cleaning Spark Plug
Electrode
FIG. 8 -Checking Spark Plug
Gap
CHECK
AND ADJUST
DISTRIBUTOR POINTS - REPLACE
AS REQUIRED
Unsnap the distributor cap retain-
ing clips, lift the distributor cap off
the distributor housing, and position
CONDITION
the cap out of the way
(if
necessary,
remove
the air cleaner
and/
or the
high
tension wire to gain access to
the
distributor).
Lift
the rotor off the cam.
Refer
to applicable
section
of the
Shop
Manual for distributor point
specifications.
INSPECTION
Replace the distributor point as-
sembly if the contacts are badly
burned or excessive metal transfer
between the points is
evident.
Metal
transfer
is considered excessive when
it equals or exceeds the gap
setting.
REMOVAL-BOSCH DISTRIBUTORS
6 CYL. AND 302 VS
1. Remove
contact breaker lead
from primary terminal connector.
2. Remove
screw
securing
contact
breaker assembly in breaker plate
and lift off contact breaker as an
assembly.
3.
The contact breaker assembly
may be
separated
by depressing the
moving
contact
spring
blade until the
terminal block is clear of the
station-
ary point.
INSTALLATION
1.
Assemble the contact breaker
assembly by depressing the contact
spring blade and pushing the mov-
able breaker on to the
stationary
breaker.
2.
Position
the
contact
breaker
assembly on to the breaker plate
and
secure with
screw.
3. Replace
contact
breaker lead on
primary
terminal.
4.
The breaker points must
strike
squarely, to align the breaker points
carefully bend the
stationary
point
bracket until full face contact is
obtained.
CAUSED BY
Incorrect
voltage regulator setting.
EXCESSIVE
METAL
TRANSFER OR PITTING
Radio condenser
installed to the distributor
side of the coil.
Incorrect alignment.
Incorrect
voltage regulator
setting.
Radio
condenser installed to the distributor
side of the coil.
Ignition
condenser of improper
capacity.
Extended operation
of the
engine
at speeds
other than normal.
81443 -C
FIG. 9
-Breaker Point Inspection
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