Air Valve Dashpot Adjustment; Accelerator Pump Rod Adjustment; Fast Idle Adjustment; Choke Rod Adjustment - Chevrolet 10 1971 Series Chassis Service Manual

ENGINE FUEL 6M-6
Fig. 16C— A ir Valve Dashpot Adjustment (4M V)

AIR VALVE DASHPOT ADJUSTMENT

4 M V (Fig. 16C)
With the vacuum break diaphragm seated, there must
be clearance as specified between the dashpot rod and
end of slot in air valve lever. Bend rod, at air valve end,
to adjust.

ACCELERATOR PUMP ROD ADJUSTMENT

2GV (Fig. 17C)
Back out idle stop screw and completely close throttle
valves in bore. Place gauge on top of air horn ring.
HOLLEY 4 1 5 0 ADJUSTMENTS (EXTERNAL)
FAST IDLE ADJUSTMENT (Fig. H I)
The fast idle adjustment must be set
NOTE:
with transmission in "Neutral."
1. Position fast idle lever on high step of fast idle cam.
2. Be sure choke is properly adjusted, and in wide open
position - engine warm.
3. Set fast idle to specified rpm as follows:
Bend fast idle lever as required on Holley Models
4150 to specified speed.
CHOKE ROD ADJUSTMENT (Fig. H2)
1. With choke plate held in wide open position, measure
distance from bottom of throttle body to center of
hole in the choke operating lever.
2. Adjust to specified dimension by bending loop at the
upper end of choke rod.
V A C U U M BREAK ADJUSTMENT (Fig. H3)
1. With air cleaner removed, install rubber band on
choke operating lever to hold in the closed choke
position.
2. With a flat tool, depress the choke diaphragm stem
until bottomed.
THROTTLE V A L V E S
FULLY C L O S E D
PUM P R O D ADJUSTMENT
Fig. 17C— Accelerator Pump Rod Adjustment (2G V)
Bend the pump rod at lower angle to obtain specified
dimension, to top of pump rod.
3. Measure from choke plate edge to air horn wall on
down stream side.
4. Bend choke diaphragm link to specified choke plate
opening.
CHOKE UNLOADER ADJUSTMENT (Fig. H4)
1. Hold choke valve in closed position by applying a
light force to the choke operating lever.
2. Rotate throttle lever to wide open throttle valve
position.
3. Bend unloader tang on throttle lever to obtain speci­
fied dimension between lower edge of choke plate (at
center) and air horn wall.
ACCELERATOR PUMP OVERRIDE
ADJUSTMENT (Fig. H5)
1. Hold throttle lever in wide open position with a rub­
ber band and hold pump lever fully compressed
(down), then measure the clearance between spring
adjusting nut and arm of the pump lever.
2. Clearance should be .015" minimum; adjust by turn­
ing nut or screw as required while holding opposite
end.
M E A S U R E F R O M TO P OF
AIR H O R N R IN G T O T O P
O F PU M P R O D
BE N D PUM P R O D
T O A D JU ST
10-30 CHEVROLET TRUCK SERVICE M NUAL
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