Chevrolet Light Duty Truck 1973 Service Manual page 442

6 M - 1 8 ENGINE FUEL
2. Rotate choke valve toward direction of closed choke
by applying force to choke coil lever.
3. Bend choke rod at point shown to give specified
opening between the lower edge of choke valve (at
center of valve) and inside air horn wall.
2GV (Fig. 5C)
Turn stop screw in until it just contacts bottom step of
fast idle cam. Then turn screw in one full turn. Place idle
screw on second step of fast idle cam against shoulder of
high step. With screw in this position, hold choke valve
toward closed position with a rubber band and check
clearance between upper edge of choke valve and air
horn wall. Adjust to specified dimension by bending tang
on choke lever and collar assembly.
4MV (Fig. 6C)
With the cam follower on second step of fast idle cam
and against the high step, rotate the choke valve toward
Fig. 3C~Fast Idle Adjustment (Manual Choke)
Fig. 2C~Fast Idle Adjustment (Rochester 4MV)
H O LD DOWN ON
CHOKE VALVE
Fig. 4C-Choke Rod (Fast Idle Cam) Adjustment (MV)
the closed position by turning the external choke lever
counterclockwise. Dimension between the lower edge of
choke valve, at choke lever end, should be as specified.
Bend choke rod to adjust (Fig.
CHOKE VACUUM BREAK ADJUSTMENTS
MV (Fig. 7C)
The following procedure for adjusting the vacuum break
diaphragm unit is used to insure correct initial choke
valve opening after engine starting:
1. Remove air cleaner assembly from vehicle. On
vehicles with "Therm AC" air cleaner, plug the
sensor's vacuum take-off port.
2. Using an outside vacuum source, apply vacuum to
the vacuum break diaphragm until the plunger is
fully seated.
GAUGE BETWEEN CHOKE
VALVE AND AIR HORN WALL
BEND ROD TO ADJUST
CAM FOLLOW ER MUST BE
HELD FIRM LY ON SECOND
STEP O F FAST IDLE CAM
AGAINST HIGH STEP
C).
6
LIGHT DUTY TRUCK SERVICE MANUAL