Chevrolet 70 1969 Series, Руководство по ремонту

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ENGINE ELECTRICAL 6Y-16
inserted into place, spiral gear will cause rotor
to turn counterclockwise. It may be necessary to
insert the assembly several times to find the cor­
rect position to bring rotor segment to No. 1 firing
position. Perform steps 3, 4, and 5 under "If
Engine Has Been Cranked” below.
IF EN G IN E HAS BEEN C R A N K E D
1. Remove left-hand valve rocker arm cover.
Turn engine over by intermittently operating start­
er and observe movement of No. 1 intake valve
(second valve from front). When intake valve starts
to close (raise up), continue to turn engine slowly
until pointer on timing gear cover is at proper
timing mark on crankshaft pulley (fig. 2). Engine
is then in No. 1 firing position.
2. Install distributor as described in Step 1
above. It may be necessary to turn the oil pump
drive shaft to permit engagement of drive shaft
with distributor drive gear.
3. Install distributor hold-down clamp and cap
screw.
4. Install distributor cap. Install spark plug
wires in cap in correct firing sequence -- 1-6-5-
4_3_2 -- starting with No. 1 wire in socket ad­
jacent to No. 1 firing position mark on distributor
housing, then proceeding clockwise around the cap.
Install secondary wire from ignition coil in center
socket in distributor cap. Connect distributor prim ­
ary wire to negative (-) terminal on ignition coil.
5. Check and adjust ignition timing as pre­
viously directed under "Ignition Timing."
DISTRIBUTOR CONDENSER
Condenser, mounted on breaker plate and c on­
nected across the points, reduces point arc by its
ability to store up electrical energy.
R E M O V A L A N D IN S T A L L A T IO N
1. Release distributor cap hold-down screws,
remove cap, and place it out of the work area.
2. Remove rotor.
3. Disconnect condenser lead wire from con­
tact point quick-disconnect terminal.
4. Remove condenser attaching screw, lift con­
denser from breaker plate, and wipe breaker plate
clean.
5. Install new condenser, using reverse of pro­
cedure outlined above.
T E S T
Four factors affect condenser operation, and
each must be considered in making tests.
Breakdown. Breakdown is a failure of insulat­
ing material, causing direct short between metallic
elements of condenser. This condition prevents
any condenser action.
Low Insulation Resistance. This condition per­
mits leakage which prevents condenser from hold­
ing its charge. A condenser with low insulation
resistance is said to be weak.
High Series Resistance. This is excessive re­
sistance in condenser circuit due to broken strands
in condenser lead or to defective connections. This
will cause burned contact points and ignition fail­
ure upon initial start and at high speeds.
Capacity. Capacity is built into a condenser
and is determined by the area of the metallic ele­
ments, and the insulating and impregnating mater­
ials. A condenser of incorrect capacity will result
in point pitting.
IGNITION COIL
Ignition coils are mounted on top of block near
front of distributor (fig. 3). Ignition coil primary
terminals are marked positive (+) and negative (-).
Wire from distributor primary terminal (black)
must be connected to the negative (-) terminal of
coil. The light green feed wire from starter sole­
noid and the special resistance wire must be con­
nected to the positive (+) terminal of coil.
IGNITION C O IL T E S T
If there is any doubt as to the condition of the
coil, it should be tested with conventional coil
tester, following instructions furnished by manu­
facturer of testing equipment. Defects indicated
by test are:
1. Open primary circuit.
2. Open secondary circuit.
3. Shorted turns in primary or secondary.
4. High voltage breakdown in secondary.
5. High resistance in primary connections.
If any of the above conditions are evident, coil
must be replaced.
SPARK PLUGS
G E N E R A L IN F O R M A T IO N
Spark plug life is governed to a large extent
by operating conditions, and plug life varies ac­
cordingly. To insure peak performance, spark
plugs should be checked, cleaned and regapped
every 5,000 miles.
Worn and dirty plugs may give satisfactory
operation at idling speed, but under operating con­
ditions they frequently fail. Faulty plugs are evi­
dent in a number of ways such as wasting gas,
power loss, loss of speed, hard starting, and gen­
eral poor engine performance.
Spark plug failure, in addition to normal wear,
may be due to dirty or leaded plugs, excessive
gap, or broken insulator.
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SH O P M A N U A L