Chevrolet 70 1969 Series, Руководство по ремонту

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ENGINE ELECTRICAL 6Y-12
Figure I — Disengaging Ignition Switch Connector
3. Remove the metal ignition switch retaining
nut from the passenger side of the dash, or from
top of transmission control island.
4. Pull ignition switch out from under dash or
transmission control island and separate wiring
connectors by inserting thin blade of small screw­
driver under each tang of wiring connector as
shown in figure 1. Pull connector from switch.
IN S T A L L A T IO N
1. Engage lock tangs of wiring connector to
switch. Make sure lock tangs are fully engaged by
trying to separate.
2. Place the switch with wiring into position
from underside of dash or transmission control
island and install switch retaining nut firmly.
3. Insert switch lock cylinder in switch hous­
ing and rotate clockwise to secure in lock position.
Figure 2— Timing Marks IV-6 Engines) (Typical)
4. Connect battery negative cable to post and
check operation of switch.
IGNITION TIMING
Timing the ignition system comprises:
(1) Initial timing -- setting distributor to permit
opening of points at correct firing intervals
- and -
(2) Manual advance adjustment -- retarding or ad­
vancing the point opening to compensate for
various grades of fuel which may be used. These
timing factors require checking and adjusting
at regular intervals, or whenever performance
of engine necessitates such action.
IM P O R T A N T : Before attempting to adjust ig­
nition timing, make sure carburetor is properly
adjusted. Disconnect vacuum line from distributor
vacuum advance unit and plug the open end of line.
N O T E : The following timing settings are rec­
ommended settings for average nation-wide regu­
lar gasoline. Timing must be retarded as required
when lower octane gasoline is used.
W IT H EN G IN E RUN N IN G
N O T E : Make sure distributor is in good con­
dition and dwell angle is properly adjusted before
checking ignition timing. If dwell angle requires
adjustment, adjust as directed later under "D is ­
tributor.”
1. Figure 2 shows location of timing marks
on the crankshaft pulley hub. Connect one lead of
a timing light to No. 1 spark plug terminal (front
plug on left side) and connect the other lead in
accordance with instructions furnished with the
instrument.
2. Start engine and run at idle.
3. Set timing to 1CP before upper-dead-center
(BUDC). If timing mark does not align with pointer,
loosen distributor mounting clamp cap screw (fig.
3) and rotate distributor body as required to syn­
chronize timing light flashes with timing mark on
engine crankshaft pulley.
4. Tighten distributor mounting clamp cap
screw after adjustment is made.
W IT H EN G IN E N O T RUN N IN G
1. Locate No. 1 cylinder spark plug wire on
distributor cap. Mark distributor body adjacent to
No. 1 wire socket in cap. Remove distributor cap.
2. Intermittently operate starter until proper
timing mark on crankshaft pulley is aligned with
pointer (fig. 2).
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SH O P M A N U A L