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CARBURETOR-W W3
14-43
Fig. 1 I 4 n s t a l l i n g Discharge Check Ball
of fuel through the hole at the bottom of the power by-
pass jet.
When the demand for power is satisfied and the
throttle opening is decreased, the manifold vacuum
builds up to raise the power piston and closes the 2nd
stage valve (lower) cutting off the supply of fuel
through the bottom hole of the jet. A further reduc-
tion of power closes the 1st stage valve (upper) cutting
off the supply of fuel through the upper hole.
No changes in service procedures are required ex-
cept to be sure the Power By-Pass Jet is clean.
(6)
Install the accelerator pump inlet check ball
(3/1s
inch diameter) in the check ball seat at the bottom of
the pump cylinder, as shown in (Fig. 10).
(7)
Install the accelerator pump discharge check
ball
(1/8
inch diameter) in the orifice in the center
passage of the discharge strut section of the main
body, as shown in (Fig. 11).
1ST STAGE
ORIFICE
OPEN
POWER BYPASS JET
POWER BYPASS JET
IST STAGE
2ND STAGE
2ND STAGEZVALVE
\
2ND STAGEZVALVE
'
CLOSED
OPEN-
61 x 9 0 A
Fig. 12-Power
By-Pass Jet
I1
s t
and 2nd Stage
Operation1
\
m
ACCELERATOR PUMP
Fig. 13-Testing
Accelerator Pump Intake and
Discharge Check Balls
Accelerator Pump Test
(1) Pour clean gasoline into the carburetor bowl,
approximately
1/2
inch deep. Remove the accelerator
pump plunger from the jar of gasoline and slide
it down into the pump cylinder. Raise the plunger and
press lightly on the plunger shaft to expel the air from
the pump passage.
(2) Using a small clean brass rod, hold the dis-
charge check ball firmly down on its seat. Again raise
the plunger and press downward. No fuel should be
emitted from either the intake or discharge passage,
as shown in (Fig. 13).
(3) If any fuel does emit from either the intake
or
discharge passages, it indicates the presence of dirt
or an imperfect check ball seat. The passage should
be recleaned and then thoroughly blown out with
compressed air. Examine the check ball seat for signs
of damage that would not allow the ball to seat prop-
erly.
(4)
Reinstall check ball and test again. If still leak-
ing, place a piece of drill rod down on ball and rap
sharply with hammer. Remove the old check ball and
install new ball. Then retest. (This operation forms a
new ball seat in the carburetor casting.)
( 5 )
Install the discharge cluster gasket, cluster and
screw. Tighten securely. See (Fig.
4).
Again depress the accelerator pump plunger. A
clear straight stream should emit from each cluster
jet. If the streams are not identical (if either one is
diverted or restricted), a new discharge cluster should
be installed.
After test, pour the gasoline from the carburetor
bowl and remove the accelerator pump plunger.
(6)
Check the float for leaks
or
damage. If satis-
factory for further service, install in position in the
carburetor bowl.
(7)
Assemble the fuel inlet needle valve, seat and
gasket, then insert in position in the main body. Tight-
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