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DISASSEMBLY, CLEANING, REPAIR AND REASSEMBLY
a.
Remove the idle speed mixture screw (14), washer
and
tension
spring.
Inspect for damaged threads (see Figure 6-8).
b. Remove the metering diaphragm cover (29), the metering dia-
phragm (28), and gasket (27).
Inspect the
cover
for nicks,
dents,
or cracks that might hamper operation.
Inspect the metering dia-
phragm; the center plate must be riveted securely to the diaphragm
and the diaphragm should be free
of
holes and
imperfect.
i ons.
The
gasket should be replaced if there are holes
or
creases on its
sealing surface.
The parts must be reassembled in the
correct
order.
The gasket should be assembled
onto
the carburetor body
casting first, then the metering diaphragm is assembled next to
the gasket.
c. Remove the hinge pin retaining screw (25), the hinge pin (23), inlet
control lever (26) and the inlet tension spring (24).
Use
caution
in
removing these parts.
Spring pressure may push the inlet
control
lever out of the casting.
Inspect the parts for wear
or damage.
The inlet control lever must rotate freely on the hinge pin.
d. Handle the inlet spring carefully. Do not stretch this spring
or
change its compression characteristics.
If
in doubt about its
condition, replace
it.
e. Remove the inlet needle (22).
Remove the inlet seat assembly
using a
3/
8-inch thin wall socket.
Remove the inlet seat
gasket.
f.
The inlet seat assembly consists of a brass
cage
and a rubber in-
sert for the inlet needle seat.
Assemble the insert into the cage
with the molded rim side away from the inlet needle point.
Some HD carburetors are
equipped
with a rubber tipped needle,
a
brass inlet seat and a copper
gasket.
The installation instructions
below apply to both types
of
inlet seats.
The inlet needles and seats are matched and tested for leaks at the
factory and the parts must be kept in matched sets. When installing
the insert cage into the carburetor body, use
a
new
gasket.
Do not
force the cage, as you may strip the threads or
distort
the insert.
Use
a torque wrench to apply 40 to 50 inch
-
pounds torque.
The needle and
seat assembly must be clean to insure correct performance.
g. Remove and inspect the pOints
of
the high speed
and
idle mixture
screws. See Figures 6-3 and
6-
4. Through misuse, either mix-
ture screw point may be bent (extruded)
from
being
forced
into
the casting seat or possible broken off in the casting (see Figure
6-5).
If
either mixture screw is damaged, be sure to inspect the
casting.
If
the adjustment seats are damaged, a new body
casting
is required. Check for clogged inlet and return line screen.
IMPORTANT
Do not alter return line
elbow
openings.
This
elbow
controls
inlet pressure and fuel flow to prevent vapor locking in carbu-
retor and fuel pump.
h. Welch plugs seal the idle by-pass ports and main nozzle ball check
valve from the metering chamber.
Accumulated dirt
can
usually
be blown out through the mixture screwholes. However, an unusu-
ally dirty carburetor requires the removal
of
these plugs. Drill
just through the welch plug carefully with a l
/
W' drill. Drilling
too deeply may ruin the casting or the ball check valve.
Use a
small punch to remove the plug.
HIGH SPEED
NEEDLE VALVE
Figure 6-3
Figure 6-4
GOOD
WORN
Figure 6-5
6-
3
1
7
14
2.
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