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ENGINE 6-10
Fig. 15 - Crank case Ventilation Valve
a. If voltage is 9 volts or more and cranking speed
is
satisfactory,
the battery, starter, cables,
starter switch and ignition circuit to coil (by-
passing resistance wire) are in good condition.
b. If below 9 volts, check circuit until difficulty is
located.
Meter reading below specification—Weak bat-
tery; defective cables, connections, switch or
starter; defective ignition circuit to coil.
Cranking speed below normal--Excessive re-
sistance in cables or starting motor; excessive
mechanical drag in engine.
Uneven cranking speed—Uneven compression,
defective starter or starter drive.
Ignition Switch
With voltmeter connected as described for the Cranking
Voltage Test, turn ignition switch to ON. Voltage should
drop to 5 to 7 volts as current is now passing through
high resistance wire connected between ignition switch
and (+) positive terminal of coil. If battery voltage of
12 volts is obtained, the starter solenoid is by-passing
the high resistance wire connected between ignition
switch and (+) positive terminal of coil, thus the starter
solenoid is not functioning properly to bypass the ignition
resistance wire or the ignition circuit is incorrectly
wired.
Distributor Resistance
Use equipment as directed by manufacturer. Excessive
(t n ti ft
Fig. 16 - Cylinder Balance Test
Fig. 17 - Testing Cranking Voltage
resistance in primary circuit must be eliminated before
continuing with test procedure.
Secondary Resistance
Use equipment as dire6ted by manufacturer.
•
Uniform "normal readings" as specified by manu-
facturer indicate all secondary circuit components
are in good condition.
•
If all readings are "below normal," check for cor-
roded coil tower terminal, poorly connected or
broken coil wire, center cap electrode or rotor tip
burned, or an open secondary in coil.
•
If readings are "higher than normal" at two or more
plugs adjacent in firing order, cross firing is oc-
curring in distributor cap or between spark plug ca-
bles concerned.
•
If meter reads off scale to left, the coil polarity is
reversed. Check for reversed coil primary wires,
wrong coil or reversed vehicle battery connections.
Ignition Output and Secondary Leakage
Use equipment as directed by manufacturer.
•
GOOD readings indicate both ignition output and
secondary insulation are good.
•
If all readings are BAD or if ignition test calibrator
cannot be adjusted to Set Line, check for high re-
sistance in primary circuit, defective distributor
points, coil or condenser.
e If readings are BAD when certain plug wires are
lifted off, check for cracks or carbon tracks in dis-
tributor cap or defective insulation on those plug
wires being lifted off.
CHEVROLET CHASSIS SERVICE MANUAL
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