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PART 9-1-GENERAL IGNITION SYSTEM SERVICE
9-15
INSULATION AND LEAKAGE
1. Turn the test selector to the
cam angle position and revolve the
chuck by hand until the distributor
breaker contacts are open
2. The cam angle meter should
show a zero reading.
If
a zero read-
ing is not obtained, a short circuit to
ground exists
A short could be caused by poor
primary or distributor-transistor lead
wire insulation, a shorted condenser
or a short between the breaker arm
and breaker plate
MECHANICAL OPERATION
1. Turn the test selector to the
SYNCHRO. position and check to
make sure the drive chuck is securely
tightened on the distributor shaft.
2. Turn the motor control switch
to the left to correspond with the
direction of rotation, as listed in the
rotation column of the distributor
specifications.
If it is necessary to reverse the
rotation of the drive motor, turn
the motor control switch to the
OFF position and allow the chuck
to come to a complete stop before
reversing the switch.
3. Adjust the rpm control to vary
the distributor speed between 400
and 4000 engine rpm or at the maxi-
mum speed of the engine on which
the distributor is used. Erratic or
thin faint flashes of light preceding
the regular flashes as the speed of
rotation is increased can be due to
weak breaker arm spring tension or
binding of the breaker arm on the
pivot pin
1·
Operate the distributor at ap-
proximately 2500 engine rpm.
5. Move the protractor scale with
Screwdriver
FIG. 27
-Centrifugal
Advance Adiustment
82010-A
the adjustment control so that the
zero degree mark on the scale is
opposite one of the neon flashes. The
balance of all the flashes should come
within
1
o, plus or minus, evenly
around the protractor scale. A larger
variation than
1
o
or erratic or wan-
dering flashes may be caused by a
worn cam or distributor shaft or a
bent distributor shaft.
DWELL ANGLE
1. Tum the cylinder selector to
the figure corresponding to the num-
ber of lobes on the cam of the dis-
tributor being tested.
2. Tum the test selector switch to
the cam angle position and operate
the distributor at approximately 1000
engine rpm.
3.
Adjust the distributor breaker
point gap to the dwell angle shown
in the specifications.
DISTRIBUTOR SPARK
ADVANCE
The spark advance is checked to
determine if the ignition timing ad-
vances in proper relation to engine
speed and load.
1. Check the contact dwell. If the
contact dwell or the breaker point
gap is not within specifications, ad-
just the breaker points.
2. Check the breaker arm spring
tension and adjust it if necessary.
SPACING WASHERS
FIG. 28-
Vacuum
Advance Adiustment
82011-A
The dual advance distributor has
two independently operated spark
advance systems. Each system is ad-
justed separately. Adjust the cen-
trifugal advance before adjusting
the vacuum advance.
Centrifugal Advance
1. Do not connect the test set vac-
uum line to the diaphragm. Set the
test set to
oo
advance and the initial
rpm setting listed in the specifications.
2. Operate the distributor in the
direction of rotation ( counterclock-
wise) and slowly increase the rpm to
the setting specified for the first ad-
vance reading listed in the specifica-
tions.
If
the correct advance is not indi-
cated at this rpm, stop the distributor
and bend one spring adjustment
bracket to change its tension (Fig.
27).
Bend the adjustment bracket
away from the distributor shaft to
decrease advance (increase spring
tension) and toward the shaft to
increase advance (decrease spring
tension). After the adjustment is
made, identify the bracket.
3. After an adjustment has been
made to one spring, check the mini-
mum advance point again.
4. Operate the distributor at the
specified rpm to give an advance just
below the maximum.
If
this advance
is not to specifications, stop the dis-
tributor and bend the other spring
bracket to give the correct advance.
5. Check the advance at all rpm
settings listed in the specifications.
Operate the distributor both up and
down the rpm range.
Vacuum Advance
1. Connect the test set vacuum
line to the fitting on the diaphragm
and turn the vacuum supply switch
on.
2. Set the test set to
oo
advance,
0 vacuum, and at 1000 rpm.
3. Check the advance at the first
vacuum setting given in the speci-
fications.
4. If the advance is incorrect,
change the calibration washers be-
tween the vacuum chamber spring
and nut (Fig. 28). After installing
or removing the washers, position
the gasket in place and tighten the
nut. The addition of a washer will
decrease advance and the removal
of a washer will increase advance.
5. After one vacuum setting has
been adjusted, the others should be
checked. Do not change the original
rpm setting when going to a dif-
ferent vacuum setting.
If
the other
settings are not within limits, it in-
dicates incorrect spring tension, leak-
age in the vacuum chamber and/ or
line, or the wrong fiber stop has been
installed in the vacuum chamber of
the diaphragm housing.
DISTRIBUTOR TESTS-
ROTUNDA RE-236 TESTER
MOUNTING DISTRIBUTOR
1. Adjust the distributor support
arm in relation to the distributor
shaft length.
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