Chevrolet 1977 10 Series, Repair Manual, Page: 216 / 468

6C-22 OVERHAUL MANUAL
MODEL 4 M V CARBURETOR
CHOKE VALVE ACCELERATOR PUMP ROD
VACUUM BREAK
FUEL INLET
IDLE MIXTURE SCREW
AIR VALVE
PART NUMBER
SECONDARY
THROTTLE LEVER
PRIMARY THROTTLE
LEVER
CURB IDLE SCREW
Fig. 6 C -6 0 ~ M o d e l 4 M V C a rb u re to r
D IS A S S E M B L Y
Place carburetor on a holding fixture to prevent damage
to throttle plates (Fig. 6C-60).
Throttle Return Control Valve (if Equipped)
Remove screws securing the throttle return control valve
and bracket assembly to float bowl and remove control valve
and bracket.
CAUTION:
The control valve should not be
immersed in any type o f carburetor cleaner and
should always be removed before complete
carburetor overhaul.
Air Horn
1. Remove horseshoe clip from upper end of choke rod.
Disconnect choke rod from upper choke shaft lever.
Fig. 6C -61-R em oving Secondary M etering Rods
Fig. 6 C -6 2 --R e m o vin g Pum p Lever
2. Remove choke rod from lower lever inside the float
bowl casting by holding lower lever outw ard with small
screwdriver and twisting rod counterclockwise.
3. Remove vacuum hose from vacuum break unit.
4. Remove secondary metering rods by removing the
small screw in the top of the metering rod hanger. Lift
upw ard on metering rod hanger until the secondary metering
rods are completely out of the air horn. M etering rods may
be disassembled from the hanger by rotating ends out of the
holes in the end of the hanger (Fig. 6C-61).
5. Using special tool J-25322, drive small roll pin (pum p
lever pivot pin) inw ard just enough until pump lever can be
removed from air horn. Then remove pump lever from pum p
rod (Fig. 6C-62).
CAUTION:
Use care in removing small roll pin to
prevent damage to pum p lever casting boses in air
horn.
6. Remove nine air horn to bowl attaching screws; two
attaching screws are located next to the venturi. (Two long
screws, five short screws, and two countersunk screws) (Fig.
6C-63).
7. Lift air horn off bowl and twist to disengage vacuum
break rod from air valve shaft lever. A ir horn gasket should
remain on bowl for removal later. (Fig. 6C-64).
8. Remove vacuum break rod from vacuum break
diaphragm plunger.
CAUTION:
Care m ust be taken not to bend the
small tubes protruding from air horn. These are
permanently pressed into the casting. Do not
remove.
Air Horn Disassembly
N O TE: F u rth er disassembly o f the air horn is not
required for cleaning purposes and is not recommended.
If part replacem ent is required, proceed as follows:
1. Remove staking on two choke valve attaching screws
and then remove choke valve and shaft.
2. Remove pum p lever roll pin.
CAUTION:
A ir valves and air valve shaft are
calibrated and should not be removed. However
;
should it be necessary to replace the plastic air valve
cam on the air valve shaft, a repair k it is available,
which includes the plastic cam, closing spring, pin,
screw and instructions.