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IGNITION SYSTEM
8-59
remove test lamp. If the operation is performed prop
erly the engine is timed to specifications.
NOTE: If the engine i s turned beyond the timing
mark, continue turning the engine for two full
revolutions of the crankshaft; this will place the
dis-
tributor rotor in approximately the initial position.
CAUTION:
DO
NOT reverse the rotation of the
crankshaft if you have passed the timing mark as
this would affect valve timing and distributor tim-
ing.
IGNITION COIL
The ignition coil is designed to operate with an ex-
ternal ballast resistor. When testing the coil for out-
put, include the resistor in tests.
Inspect the coil for external leaks and arcing. Al-
ways make two tests when testing the coil. One when
the coil is cold, the other after the coil has been
warmed up.
Test the coil according to the coil tester Manu-
facturer's instructions. Test the coil primary resist-
ance. Test the ballast resistor resistance. Test the coil
secondary resistance. Replace any coil and ballast re-
sistor that does not meet specifications.
Every time an ignition coil is replaced because of
a burned tower, carbon tracking or any evidence of
arcing at the tower, the nipple or boot on the coil end
of the secondary lead should be replaced. Any arcing
at the tower will carbonize the nipple
so that placing
it on a new coil will invariably cause another coil
failure.
If the secondary lead shows any signs of damage,
the lead should be replaced with a new lead with the
neoprene nipple since the old lead can cause arcing,
and therefore, ruin a new coil.
BALLAST RESISTOR
The ballast resistor is
a compensating resistance in
the ignition primary circuit. During low speed opera-
tion, when the primary circuit current flow is as high,
the ballast resistor temperature rises, increasing the
resistance. This reduces the current flow, thereby pro-
longing ignition contact life. At high speed operation,
when the primary current flow is low, the ballast
resistance cools
o f f
allowing more current flow, which
is required for high speed operation. During starter
operation, the ballast resistor is bypassed, allowing full
battery voltage to the ignition primary circuit.
SPARK PLUGS
To insure peak performance, spark plugs should
be
removed, cleaned, tested and regapped periodically,
depending on driving conditions. Worn and dirty
plugs may give satisfactory operation at idling speed
but may fail under operation conditions. Spark plug
Fig.
I-Normal
Conditions
appearance or conditions can reflect a wide variety of
engine conditions as follows:
Normal Conditions
Normal conditions are shown in Figure 1. This
plug has been running at the correct temperature in a
"healthy" engine. The few deposits present will prob-
ably be light tan or gray in color with most regular
grades of commercial gasoline. Electrode burning will
not be in evidence; gap growth will average not more
than about .001"/1000 miles. Chances are the plug,
as pictured, could be cleaned, the gap electrodes filed,
regapped and reinstalled with good results.
Cold
Fouling
Cold fouling or carbon deposits, (Fig.
2).
This
dry
black appearance
is
fuel carbon and can be due to
over rich fuel-air mixture, possibly resulting from
a faulty choke, clogged air cleaner, improper carbu-
retor idle adjustment, or dirty carburetor. However,
if
only one or two plugs in a set are fouled like this
it's a good idea to check for sticking valves or de-
fective ignition leads. This condition also results
from prolonged operation at idle. If the car is op-
erated extensively at idle and low speeds, improved
plug service will
be
obtained by using the next step
hotter spark plugs.
Wet Fouling
Wet fouling, (Fig. 3) tells you that the plug has
Fig. 2-Cold
Fouling
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