Chevrolet 1977 10 Series, Руководство по ремонту, Страница: 212 / 468

6C-18 OVERHAUL MANUAL
Fig. 6 C -5 2 --R e m o vin g T h ro ttle B o d y
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 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 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 pum p passages and jets for dirt, im proper
seating inlet or discharge balls, scores in pum p well.
Fig. 6C-53~Removing Insulator Gasket
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 for leaks.
3. Clean or replace carburetor filter.
4. Inspect needle for sticking, dirt etc.
5. Exam ine fast idle cam for wear or damage.
6. Also check items under "flooding".
d. Poor Perform ance - 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 m ating surfaces on castings for damage
to sealing bends, nicks and burrs.
3. Clean all idle fuel passages.
4. Check throttle lever 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
prelim inary idle adjustment. Final adjustm ent m ust be made
on the engine using the procedures described under slow 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 tow ards throttle lever.
Float Bowl Assembly
1. Install new throttle body to bowl gasket over two
locating dowels on bowl.
2. Install throttle body making certain throttle body is
properly located over dowels on float bowl, then install
throttle body to bowl screws and tighten evenly and securely
(Fig. 6C-52).
3. Place carburetor on proper holding fixture J-8328.
4. Install fuel inlet filter spring, filter, new gasket and
inlet nut and tighten nut to 18 pounds feet (Fig. 6C-51).
CAUTION: The fuel inlet check valve on a vehicle
with light duty emissions m ust be installed in the
filter to meet M otor Vehicle Safety Standards
(M. V.S.S.) for roll-over. New service replacement
filter includes the check valve.
NOTE:
Ribs on closed end of filter element prevent filter
from being installed incorrectly unless forced.
CAUTION: Tightening beyond specified torque can
damage nylon gasket.
Choke
1. Install new cup seal into plastic insert on side o f float
bowl for interm ediate choke shaft. Lip on cup seal faces
outward.
2. Install secondary throttle valve lock-out lever on boss
on float bowl with recess in hole in lever facing inward.
3. Install new cup seal into inside choke housing shaft
hole. Lips on seal face inward, tow ards inside of housing.
4. Install fast idle cam onto the interm ediate choke shaft
(steps on fast idle cam face downward) (Fig. 6C-50).
5. Carefully install fast idle cam and intermediate choke
shaft assembly through seal in choke housing; then install