GMC 1976 ZEO 6083 Maintenance Manual page 422

6Y- 4 2 ENGINE ELECTRICAL
Figure 42-Vacuum Advance Unit
DISTRIBUTOR REMOVAL
1 . Disconnect the distributor wire from coil.
2. Remove distributor cap as shown in Figure 35 .
NOTE :
If necessary to remove secondary wires
from cap, note position on cap tower for lead to
No . 1 cylinder . This will aid in installation of
leads. (figure 32)
3 . Remove vacuum hose line from vacuum ad-
vance unit .
4. Remove distributor clamp screw and hold-
down clamp.
5 . Note position of rotor, then pull distributor up
until rotor just stops turning counterclockwise and
again note position of rotor.
NOTE :
To insure correct timing of the distribu-
tor, the distributor must be INSTALLED with
the rotor correctly positioned as noted in Step 5 .
If the engine has been turned after the distributor
was removed, it will be necessary to install a jumper
wire and crank engine until the timing mark on the
harmonic balancer indexes with the 0 degree timing
mark on the engine front cover. If both valves of the
No . 1 cylinder are closed, the piston will be on top
dead center in either the firing or exhaust stroke.
Install distributor so that the rotor is pointing to No .
1 spark plug terminal in the cap when the distributor
is fully seated . Install clamp and bolt, start engine . If
engine fails to start or runs uneven, distributor is 180
degrees out of time . Lift up distributor, turn rotor
one half revolution and install distributor .
Figure 43-Removing Roll Pin
DISTRIBUTOR DISASSEMBLY
1 . Mark distributor shaft and gear so that they
may be reassembled in the same position .
2 . Drive out the roll pin. (figure 43)
3 . Pull the distributor assembly from the gear and
pull the distributor shaft and breaker cam from the
housing.
4. Remove the retaining ring from the upper
bushing afid lift the breaker plate and felt wick from
the bushing. (figure 44)
GEAR PRIMARY GROMMET
LEAD /
~VACODM CONTROL
CAM, WEIGHT BASE,
WEIGHTS AND SPRINGS
44
A-1876
Figure 44-Distributor Disassembled