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CARBURETOR-BBS
14-17
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. See (Fig.
8).
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 valve would be
obtained. Changing the relationship of the valve to
the ports would adversely affect normal car operation
between the speeds of 15 and 30 miles per hour.
However, if it has been determined that a new shaft
or valve is to be installed, adhere to the following in-
structions:
(2) Mark the position of the throttle valve in the
bore, so that it can be reinstalled in the same posi-
tion.
(3) Remove the screws that hold the throttle valve
to the shaft, then slide the valve out of the bore.
CAUTION:
These screws are staked on the oppo-
site 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.
(5) Install new throttle shaft and lever (or new
valve).
(6)
Install NEW screws but do not tighten. Hold the
valve in place, with the fingers pressing on the high
side of valve. Tap the valve lightly with a screwdriver
to seat in the throttle bore. Now tighten the screws
securely and stake by squeezing with pliers.
(7)
Install the idle mixture screw and spring in the
throttle body. (The tapered position must be straight
and smooth. If the tapered portion is grooved or
ridged, a new idle mixture screw should be installed
to insure having correct idle mixture control).
Do not
use a screwdriver.
Turn the screw
lightly
against its
seat with the fingers. Back off
1 full
turn for approxi-
mate adjustment.
Main Body
(1)
Install the accelerator pump discharge and in-
take check balls in their respective passages, as
IDLE TRANSFER PORT
SPARK ADVANCE
IDLE SPEED
INTROL PORT
A
ADJUSTING
FAST IDLE SPEED
ADJUSTING SCREW
VENT
64
x
272
i C
D W U l
HOLE
Fig. 8-Ports
in Relation
to
Throttle Valves
INSTALL THE ACCELERATOR PUMP INLET
VECK BALL AT EOTTOM OF CYLINDER
ACCELERATOR PUMP
RDISCHARLE PASSAGE
- ,
2 & 4
0
//
N K647
Fig. 9-Installing
Accelerator Pump Discharge
and Intake Check Balls
shown in (Fig. 9).
To check the accelerator pump system fuel inlet
and discharge check balls proceed as follows:
(2)
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.
(3) Using a small clean brass rod, hold the dis-
charge check ball down firmly 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. 10).
If any fuel does emit from either passage, it indi-
cates the presence of dirt or a damaged check ball.
Clean the passage again and repeat test. If leakage is
still evident, install a NEW check ball. The fuel inlet
check ball is located at the bottom of the plunger
well.
APPROXIMATELY
i
12
INCH
-
OF
FUEL IN THE BOWL
64
x
274
Fig.
1 O-Testing Accelerator Pump Intake and
Discharge Check Balls
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