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14-26
CARBURETOR-BBD
1
' / 4
INCH
CAUTION: These screws are staked on the opposite
side and care should
be
used at removal so as not
to break off in the shaft.
(4)
Slide the throttle shaft out of the throttle body.
Remove the
fast
idle speed screw lever.
(5) Slide the fast idle speed screw lever over new
throttle shaft and insert into throttle body.
(6)
Install throttle valves in their respective bores
(with the valve numbers toward manifold flange). In-
stall
NEW
screws but do not tighten. Hold the valves
in
place, with the fingers pressing on the high sides of
the valves. Tap the valves lightly with a screwdriver
to seat valves in the throttle bores. Tighten the screws
securely and stake by squeezing with pliers.
(7) Install the idle mixture screws and springs in the
throttle body. (The tapered portion must be straight
and smooth. If the tapered portion is grooved or
ridged, new idle mixture screws should be installed to
insure having correct idle mixture control).
Do Not
Use a Screwdriver.
Turn the screws
lightly
against
their seats with the fingers. Back
off
1 full turn for ap-
proximate adjustment.
Main Body
(1) Invert the main body and place the insulator in
position, then place the throttle body on main body
and align. Install screws and tighten securely.
(2)
Install the accelerator pump discharge check
ball
("Is2
inch diameter) in the discharge passage, as
shown in (Fig. 7). Drop the accelerator pump intake
check ball
inch diameter) into the bottom of the
pump cylinder.
To check the accelerator pump system; fuel inlet
and discharge check balls, proceed as follows:
(3) Pour clean gasoline into the carburetor bowl,
approximately
Y 2
inch deep. Remove the pump plung-
er from the
jar of gasoline and slide down into the
pump cylinder. Raise the plunger and press lightly on
the plunger shaft to expel air from the pump passage.
(4)
Using a small clean brass rod, hold the
dis-
charge check ball down firmly on its seat. Again raise
ACCELE
INTAKE
AT
O F
Fig. 8-Testing
Accelerator Pump Intake and
Discharge Check Balls
the plunger and press downward.
No
fuel should be
emitted from either the intake
or
discharge passage,
as shown in (Fig. 8).
If any fuel does emit from either passage,
it
indi-
cates the presence of dirt or a damaged check ball
or
seat. Clean the passage again and repeat test. If
leakage is still evident, install new check balls. The
fuel inlet check ball is located at the bottom of the
plunger well. Remove fuel from bowl.
(5)
Install new gaskets on venturi cluster, then in-
stall in position in the main body. Refer to (Fig.
5).
Install the cluster screws and tighten securely.
(6)
Install the main metering jets and tighten se-
curely. Refer to (Fig.
4).
(7) Before installing the step-up piston, be
sure
the
step-up rods are able to move freely each side of the
vertical position, as shown in (Fig. 9). The step-up rods
must be straight and smooth.
(8) Slide the step-up piston gasket down into posi-
tion in the piston well, then install the step-up piston
spring and step-up piston and rods. Carefully guide
the step-up rods into the main metering jets.
Refer
to
STEP-UP PISTON
STEP-UP
RODS
T MOVE FREELY
Fig. 7 4 n s t a l l i n g Accelerator Pump Discharge
Check Ball
Fig. 9-Step-up
Piston and
2
Stage
Rods
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