Chevrolet Chevelle 1977 Repair Manual page 205

Fig. 6 C -31 ~ C h o ke H o u sin g A s se m b ly
1. Thoroughly clean all metal parts and blow dry with
compressed air. M ake sure all fuel passages and metering
parts are free of burrs and dirt.
2. Check, repair or replace the following parts if the
following problems were encountered.
a. Flooding
1. Inspect float needle seat for dirt, deep wear grooves,
scores and proper seating.
2. Inspect float, float arm and hinge pin for distortion,
binds and burrs. Check float for leaks an d /o r being loaded
(heavier than normal).
b. Hesitation
1. Inspect pump plunger for cracks, scores or cup,
excessive wear. A used pum p cup will shrink when dry. Soak
in fuel for 8 hours before testing if dried out.
2. Inspect pump duration and return spring for being
weak or distorted.
3. Check all pump passages and jets for dirt, improper
seating inlet or discharge balls, scores in pump well.
4. Check linkage for excessive wear, repair or replace as
necessary.
c. H ard Starting - Poor Cold Operation
1. Check choke valve and linkage for excessive wear,
binds or distortion.
2. Inspect choke vacuum diaphragm for leaks.
3. Clean or replace carburetor filter.
4. Inspect needle for sticking, dirt, etc.
5. Examine fast idle cam for wear of damage.
6. Also check items under "flooding".
d. Poor Performance - Poor Gas Mileage
1. Power Piston, power valve, metering rods for dirt,
sticking, binding, damaged parts or excessive wear.
2. Clean all fuel and vacuum passages in castings.
e. Rough Idle
1. Inspect idle needle for ridges, burrs or being bent.
2. Inspect gasket mating surfaces on castings for damage
to sealing bends, nicks and burrs.
CARBURETOR
3. Clean all idle fuel passages.
4. Check throttle lever and valves for binds, nicks and
other damage.
A S S E M B L Y
Throttle Body
1. Install idle speed screw and spring assembly in throttle
body if removed.
2. If it was necessary to remove the idle mixture needles,
install the idle m ixture needles and springs into the throttle
body until finger tight and seated. Back out screws four turns
as a preliminary idle adjustment.
3. Install new rubber dust seal into cavity inside choke
housing. Lip on seal faces towards carburetor after the
housing is installed.
4. Install inner choke coil lever and shaft assembly into
choke housing.
5. W ith the choke coil lever and shaft assembly installed
into housing, install the interm ediate choke lever on flats of
intermediate choke shaft and retain with screw. Tighten
securely.
6. Install new choke housing to carburetor gasket.
7. Position choke housing on throttle body and retain
with two attaching screws. Tighten securely.
8. Before installing the choke cover coil and baffle plate
assembly, refer to intermediate choke rod adjustment
(Service) to adjust interm ediate choke rod so that with the
choke valve closed, the lever inside the choke housing lines
up with gauge.
9. Install choke therm ostatic coil and cover assembly
with new gaskets and end of coil below plastic tang on the
inner choke housing lever. Refer to autom atic choke coil
adjustment (Service) to index cover. Install three choke
therm ostatic coil retainers and screws. Tighten securely.
10. Place a new gasket on the bottom of the float bowl
with holes in gasket aligned with holes in casting, then
position the throttle body on gasket and install the three
attaching screws. Tighten screws evenly and securely.
Float Bowl (Fig. 6C-32)
1. Install two main metering jets and vacuum operated
power valve into bottom of float bowl. Tighten securely.
2. D rop small alum inum inlet check ball into hole in
pump well.
3. Install pum p return spring, pressing with finger to
center in pum p well.
4. D rop steel pum p discharge ball into pump discharge
hole located beneath the venturi cluster. Ball is 3/16"
diameter (do not confuse with aluminum inlet ball). Install
pump discharge ball spring and "T" retainer.
5. Install plastic main well inserts into the main fuel
wells located beneath the venturi cluster and make sure they
are seated in recesses provided. Then install venturi cluster
and gasket, tighten three screws evenly and securely. Make
certain center screw is fitted with a gasket to prevent pump
discharge leakage.
Air Horn
1. Install the upper choke rod lever and collar assembly
on to choke shaft. Then install the choke shaft assembly into
the air horn from the throttle lever side. Then install the
choke valve onto the choke shaft with part number facing
upward.
Install the choke valve attaching screws. Center the
choke valve before tightening choke valve screws. Tighten
6C-11