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IGNITION SYSTEM
8-57
TESTING CONTACT ARM
SPRING TENSION
(1)
Hook a spring scale Tool MTU-36 on the break-
er arm and pull in a straight line at right angles to
the point surfaces (Fig. 9). Take a reading as the
points start to separate under the slow and steady pull
of the scale. The spring tension should be 17 to 20
ounces. If the reading is outside these limits, loosen
the screw which holds the end of the movable arm
contact spring and slide the end of the spring in or
out, as necessary to adjust tension.
(2)
Retighten the screw and measure the spring
tension.
NOTE: Spring tension that i s too great, will cause
excessive wear on the distributor cam and on the
nylon block of the movable contact arm. Spring
tension that is too weak, is unable to keep the con-
tacts in contact with each other when they close.
This
is particularly true as engine speed is in-
creased, causing high-speed misfiring.
INSTALLING AND ALIGNING
CONTACTS
(1)
Remove the old contacts and install a new set.
Touching the contact faces with fingers during in-
stallation will cause burning of contacts during o p
eration.
(2)
Align the contacts to obtain center contact, by
bending the stationary contact bracket only.
Never
bend
the movable arm to obtain alignment.
(3) After aligning the contacts, readjust the contact
clearance to specifications using a dial indicator (Fig.
10).
(4) Test the dwell angle to show proper degrees of
closure. See "Distributor Point Dwell." The lock screw
should be loosened just enough so that the stationary
bracket can be moved with a slight drag; otherwise,
DIAL INDICATOR
ARM
' \
Y
61xl48A
Fig. 1 L A d j u s t i n g Point Clearance with Indicator
it will be difficult to set the contacts accurately. After
setting the contacts to the correct gap, tighten the
lock screw.
DISTRIBUTOR LUBRICATION
(1)
Add
3
to 5 drops of SAE 1OW oil to the oiler
on the outside of the distributor base.
(2)
Lubricate the felt pad under the rotor in the
top of the distributor cam with
3
to
5
drops of SAE
1OW oil.
(3) Wipe all old grease from surface of the dis-
tributor cam. Apply a light film of new distributor
cam lubricant number 1473595.
NOTE: Do not over-lubricate. Excess grease will
be
thrown from the distributor cam when the engine
is running. Should this grease strike the contact
faces, arcing and burning of the contacts will result
and ignition trouble will be experienced.
TESTING DISTRIBUTOR ADVANCE
Centrifugal Advance Curve
Note the model number of the distributor and re-
fer to the specifications before making this test.
Mount the distributor assembly (less cap and ro-
tor) in a reliable stroboscope-type distributor tester
and proceed with tests as follows:
NOTE: Clamp around the rib section of the distrib-
utor housing. The bottom section of the distributor
housing
is
not a machined surface and concentricity
would be affected, causing a wobble.
(1)
Turn the Tach-Dwell switch to the
8
"LOBE" po-
sition and the Motor Switch to correct direction of
rotation. Refer to "Distributor Advance Specifica-
tions" in this Manual.
(2)
Turn the battery switch "ON."
(3) Regulate the tester speed control to operate the
distributor at
200
distributor rpm.
(4) Hold the distributor contact plate in the full re-
tard position and align the "0" of the distributor test-
er degree ring with any one of the arrow flashes.
(5)
Adjust the tester speed control to operate the
distributor at speeds called for under "Specifications"
and observe arrow flashes opposite tester degree ring
to determine degrees of advance.
(6)
If the advance is not according to specifications,
corrections can be made by bending the primary and
secondary spring tabs to increase or decrease the
spring tension. The governor spring tabs can be
reached through the access hole at the breaker plate.
Rotate the shaft until the proper spring and tab
line up with the access holes. Insert a screwdriver
blade through the access hole and bend the spring
tab toward the distributor cam to decrease spring ten-
sion and advance to spark, or away from the distrib-
utor cam to increase the spring tension and retard
the spark.
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