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CARBURETOR-BBD
1
' / z
INCH
14-33
(16) Remove the screws that attach the throttle
body to the main body. Separate the bodies and dis-
card the gasket.
The carburetor now has been disassembled into
three sub-assemblies, the air horn, main body and
throttle body and the components of each disassem-
bled as far as necessary for cleaning and inspec-
tion.
It is usually not advisable to remove the throttle
shaft or valves from the throttle body, unless wear
or damage necessitates the installation of new parts.
There is about .005 inch clearance between the throt-
tle shaft and the throttle shaft bores in the throttle
body. Any clearance over .010 inch is excessive and a
new throttle shaft and/or throttle body should be in-
stalled
.
INSPECTION AND ASSEMBLY
Throttle Body
(1) Inspect the throttle shaft and throttle body for
excessive wear. If either or both are worn to the
point where the carburetor operation will be affected,
replace as required.
During manufacture, the location of the idle trans-
fer port and the spark advance control ports to the
throttle valve, is carefully established for one particu-
lar assembly, refer to (Fig. 5).
If a new shaft should be installed in an old, worn
throttle body, it would be very unlikely that the origi-
nal relationship of the ports to the valves would be
obtained. Changing the relationship of the valves to
the ports would adversely affect normal car opera-
tion between the speeds of 15 and 30 miles per hour.
If it has been determined, however, that a new shaft
or valves is to be installed, adhere to the following
instructions:
(2)
Mark the position of the throttle valves in the
bores. Be sure the idle speed screw
is
backed off.
(3) Remove the screws that hold the throttle valves
to the shaft and slide the valves out of the bores.
NOTE: These screws are staked on the opposite side
and care should be used at removal so as not to
break off in the shaft.
SPARK
ADVANCE PORT
/
THROTTLE
Fig. 5-Ports
in Relation to the Throttle Valves
Remove the staked end of the screws with a file.
(4) Slide the throttle shaft and lever out of the body.
(5) Install new throttle shaft and lever.
(6) Install throttle valves in their respective bores
(with the valve numbers toward the manifold). Install
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 in the throttle bores. Tighten the screws se-
curely 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 in-
stalled to insure having correct idle mixture control).
Do
not use a screwdriver.
Turn the screws
lightly
against their seats with the fingers. Back off one full
turn for approximate adjustment.
Main Body
(1) Invert the main body and place a new gasket in
position and place the throttle body on the main
body and align. Install screws and tighten securely.
(2)
Install the accelerator pump discharge check ball
in the discharge passage and check the accelerator
pump system, fuel inlet and discharge check balls
as follows:
(3) Pour clean gasoline into the carburetor bowl,
approximately lh inch deep. Remove the pump plung-
er from the jar of gasoline, flex the leather several
times, then slide down into the pump cylinder. Raise
the plunger and press lightly on the plunger shaft to
expel all 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
ACCELERATOR PUMP
EMITTED PAST
KE CHECK BALL
NO FUEL TO BE EMITTED
PAST DISCHARGE
CHECK BALL
NK616
Fig. &Testing
the Accelerator Pump Intake and
Discharge Balls Check
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