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8-58
IGNITION SYSTEM
NOTE:
The light tension spring controls the lower
end of the advance curve, and the heavier spring
controls the upper end of the advance curve.
Vacuum Diaphragm Leak Test
With distributor mounted in distributor tester and
with the vacuum unit attached to the distributor, pro-
ceed as follows:
'
(1) Place the thumb over the end of
the vacuum
pump and hose and adjust the regulator control
knob to give a reading 20 inches with hose closed
off to
be sure tester hose does not leak.
(2) Attach the tester vacuum pump hose to the tube
on the distributor vacuum unit. The vacuum gauge
should hold on maximum vacuum obtainable if no
leak exists.
(3)
Observe the contact plate while performing the
leak test to test response of the contact plate. There
should
be
instant response to the pull of the dia-
phragm, moving the plate without a drag or bind.
(4)
If leakage is indicated, replace the vacuum unit
assembly.
Vacuum Advance Curve
Connect the tester vacuum pump hose to the dis-
tributor vacuum advance unit and perform operations
1 through
5
under "Centrifugal Advance Curve." Then
proceed as follows:
.
(1) Turn the tester vacuum pump
"ON." Adjust
the vacuum pump regulator to vacuum test specifica-
tions. See "Specifications" and observe the arrow
flashes on the tester degree ring to determine the de-
grees of advance.
(2) If the vacuum advance
is above or below speci-
fications, replace the vacuum advance unit. Retest
the vacuum advance curve.
INSTALLATION OF DISTRIBUTOR
(1)
Position the distributor on the engine. Align
the
rotor with marks previously scribed on the dis-
tributor housing.
(2)
Engage the tongue of the distributor shaft
with the slot in the distributor and the oil pump drive
gear.
NOTE: If the engine has been cranked while the
distributor is removed, it will be necessary to estab-
lish the proper relationship between the distributor
shaft and the NO. 1 piston position as follows:
(a) Rotate the crankshaft until the number one pis-
ton
is
at top of the compression stroke.
(b) Rotate the rotor to the position of the number
one distributor cap terminal.
(c) Lower the distributor into the opening, connect
the primary lead and install the distributor cap. Make
sure
all high tension wires "snap" firm in the cap
towers. Install the distributor hold-down clamp screw.
Tighten the screw finger tight.
(d) Connect the secondary lead of a Power Timing
Light to the NO. 1 spark plug (using proper adapter).
Connect the red primary lead to the positive termi-
nal of the battery and the black primary lead to the
negative battery terminal.
(e) Start and operate the engine at idle speed. Ro-
tate the distributor housing
so that the specified
timing mark and the pointer are in alignment (Mov-
ing the distributor housing against the shaft rota-
tion advances the timing and with the shaft rotation
retards the timing).
(f)
At low altitudes, with any good grade of the
recommended gasoline, either "regular" or "premi-
um," the engine will give its best performance if timed
according to specifications.
When using low grade fuels, or after carbon has
accumulated, objectionable spark ping may occur with
the specified timing. In cases of this nature, ignition
timing should be retarded, but not to exceed
5 de-
grees of crankshaft rotation later than specified.
At high altitudes or when using higher quality gaso-
line, for example, "premium" where "regular" is
specified or "super premium" where "premium" is
specified, there is less tendency for spark ping. In
such cases, improved performance may
be
obtained
by advancing the spark not to exceed
5
degrees of
crankshaft rotation ahead of specified timing.
Within the foregoing limits, namely, from
5
de-
grees ahead to
5
degrees later than specified timing,
a good rule to follow
is
to advance the spark until
a slight ping is heard when accelerating to
15
mph
in direct drive at wide open throttle, with hot engine.
(g) Tighten the distributor clamp screw after the
timing has been set and recheck the timing adjust-
ment with a Power Timing Light.
(h) If the timing
is correct, connect the vacuum
hose to the distributor and remove the timing light
from the engine.
Ignition Timing
(with C-744
Test Lamp)
(1) Connect the
C-744
test lamp between the dis-
tributor primary terminal and the battery positive
post.
(2)
Turn engine until the number
6
exhaust valve
is just closing; continue turning the engine slowly
un-
til the specified degree mark on the crankshaft pulley
is at the pointer.
(3)
Loosen the distributor clamp bolt
so
that the
distributor housing can be rotated with a slight drag,
then turn the distributor in the normal rotation until
the test lamp lights.
(4)
Turn the distributor against normal distributor
rotation until the test lamp goes out.
NOTE: If the test lamp lights immediately whon
connected, turn the distributor against normal dis-
tributor rotation until light goes out.
(5)
Tighten the distributor clamp bolt securely and
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