Chevrolet Chevelle 1977 Repair Manual page 219

bushing in bowl will w ithstand normal cleaning. Rinse
thoroughly after cleaning.
1. Thoroughly clean all metal parts and blow dry with
compressed air. Make 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 arms and hinge pin for distortion,
binds and burrs. Check float for leaks a n d /o r being loaded
(heavier than normal).
b. Hesitation
1. Inspect pum p plunger for cracks, scores or cup,
excessive wear. A used pump 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 pum p 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 s for leaks.
3. Clean or replace carburetor filters.
4. Inspect needle for sticking, dirt, etc.
5. Examine fast idle cam for wear or 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. (If used) Check air valve for binds and damage. If air
valve is damaged, the air horn assembly must be replaced.
A torsion spring kit is available for repairs to air valve closing
spring. A new plastic secondary metering rod cam is included
in kit.
3. 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 beads, nicks and burrs.
3. Clean all idle fuel passages.
4. Check throttle levers and valves for binds, nicks and
other damage.
ASSEMBLY
Throttle Body
1. If removed, install idle m ixture needles and springs
until seated. Back out the m ixture needles 4 turns as a
preliminary idle adjustment. Final adjustm ent must be made
on the engine using the procedures described under idle
adjustment.
2. Install lower end of pum p rod in throttle lever by
aligning tang on rod with slot in lever. End of rod should
point outw ards toward throttle lever.
Float Bowl
1. Install new throttle body to bowl gasket over two
locating dowels on bowl.
2. Install throttle body m aking certain throttle body is
properly located over dowels on float bowl, then install
throttle body to bowl screws and tighten evenly and securely
CARBURETOR
(Fig. 6C-69).
3. Place carburetor on proper holding fixture J-8328.
4. Install fuel inlet filter spring, filter, new gasket and
inlet nut and tighten nut securely (18 ft. lbs.).
C A U T IO N :
damage nylon gasket.
5. If vacuum break diaphragm was removed from
bracket, slide vacuum break diaphragm between retaining
ears and bend ears down slightly to hold securely.
6. Install secondary lock-out lever.
7. Install fast idle cam on vacuum break assembly. Be
sure arm of vacuum break lever is located beneath the tail
of the fast idle cam.
8. Install vacuum hose to connection on bowl and
vacuum break assembly.
NOTE:
D o not attach vacuum hose to inlet on vacuum
break diaphragm until after vacuum break adjustm ent
is complete. (Refer to Service M anual for adjustm ent
procedure).
9. Connect choke rod (plain end) to choke rod actuating
lever, then holding choke rod with grooved end pointing
inward - position choke rod actuating lever in well of float
bowl and install choke assembly, engaging shaft with hole in
actuating lever. Install retaining screw and tighten securely.
Remove choke rod from lever for installation later.
10. If removed, install air baffle in secondary side of float
bowl with notches tow ard the top. Top edge of baffle m ust
be flush with bowl casting.
11. Install pum p discharge check ball and retainer screw
in passage next to pum p well. Tighten retainer securely.
12. Install main m etering jets. If removed, the jets should
be installed in the same hole from which they were removed.
13. If fuel inlet needle seat was removed, use new needle
seat gasket and position new seat on Fuel Inlet Needle Seat
Remover and Installer, J-22769. Carefully thread needle seat
into float bowl. Tighten securely.
14. To make adjustm ent easier, bend float arm upward
at notch in arm before assembly.
15. Install needle by sliding float lever under needle pull
clip-—correct installation of the needle pull clip is to hook
the clip over the edge of the flat on the float arm facing the
float pontoon (Fig. 6C-70).
W ith float lever in pull clip, hold float assembly at toe
and install retaining hinge pin from A.P.T. metering side
(ends of retaining pin face the accelerating pump well).
CAUTION:
holes in float arm. Severe flooding will result.
16. Adjust Float Level:
FLOAT LEVEL (Fig. 6C-71)
a. Hold float retainer firmly in place.
b. Push float down lightly against needle.
c. W ith adjustable T-scale, gauge from top of float bowl
casting (air horn gasket removed) to top of float - gauging
point is 3/16" back from end of float at toe (See inset - Fig.
6C-71).
d. Bend float arm as necessary for proper adjustment by
pushing on pontoon.
specification.
c. Visually check float alignment after adjustment.
17. Install power piston spring in power piston well. If
main metering rods were removed from hanger, reinstall
making sure tension spring is connected to top of each rod.
Install power piston assembly in well with metering rods
Tightening beyond specified torque can
Do not install float needle pull clip into
Refer to Service
6C-25
M anual for