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14-62
CARBURETOR-AFB
tle
valves to the throttle shaft and slide valve (or
valves) out of bores.
The primary valves and secondary valves are not
interchangeable and should be kept separate in order
that each may be returned to
its
respective bore. (See
Fig. 8).
INSPECTION A N D ASSEMBLY
(1) Slide the primary throttle valve (or valves) into
their respective bores, install new screws, but do not
tighten. Be sure the idle speed adjusting screw is
backed out. Hold the valves in place with fingers.
(Fingers pressing on the high side of valves.)
(2)
Tap the valves lightly in this position, tighten
screws securely. Stake screws by squeezing with
pliers.
(3) Install the two idle mixture adjusting screws
and springs in the throttle body portion of the cast-
ing. The tapered portion must be straight and smooth.
If the tapered portion is grooved or ridged, a new
idle mixture adjusting screw should be installed to in-
sure having correct idle mixture control.
Do not use a
screw driver.
The adjustment should be made with
the fingers. Turn the idle mixture adjusting screws
lightly against their seats, then back off one
full
turn
for an approximate adjustment.
(4)
Install the velocity valves and counterweights
in position in the secondary throttle bores. (Be sure
that the valve shaft is free and does not bind after
installing the secondary venturis.)
(5) Place new secondary venturi gaskets in posi-
tion, then install the secondary venturi (pump and
choke side) by lowering straight down on gaskets. In-
stall attaching screws and tighten securely.
NOTE: Be
sure all the metering holes and vent
tubes are clean, in both the primary and secondary
venturi.
(6)
Place new primary venturi gaskets in position,
then install the primary venturi (pump and choke
side) by lowering straight down on the gaskets. Refer
to (Fig. 5). Install attaching screws and tighten se-
curely.
(7)
Install the primary and secondary main meter-
ing jets, using Tool T109-58. Refer to (Fig.
4).
Tighten
jets securely.
(8) Install the accelerator pump intake check ball
using Tool T-109-59.
Accelerator Pump Test
(1)
Pour clean gasoline into the carburetor bowl
(approximately
V 2
inch deep). Remove the accelerator
pump plunger from the jar of gasoline. Flex the leath-
er several times, then slide into the pump cylinder.
(2)
Install the accelerator pump discharge check
needle in the discharge passage. Raise the pump
plunger and press lightly on the plunger shaft to ex-
pel air from the pump passages. Using a small clean
brass rod, hold the discharge check needle firmly on
its seat. Again raise the plunger and press downward.
No fuel should be emitted from either the intake or
discharge passage.
(3) If fuel does emit from the intake passage, re-
move the intake check ball and reclean the passage.
Fuel leakage at the discharge check needle indicates
the presence of dirt or a damaged check needle. Clean
again and then install a new check needle. Retest for
leakage.
(4)
If either the intake check assembly
or
discharge
check needle leaks after above test and service
fix,
attempt to reseat as follows:
Intake Check
Ball
Remove the intake check assembly from the throt-
tle body. Install a new check assembly, then
retest
as
described previously.
Discharge Check Needle
(1)
With the discharge check needle installed, in-
sert a piece of drill rod down on the needle. Lightly
tap the drill rod with a hammer to form a new seat.
Remove and discard old needle and install a new one.
Retest as described previously. If the service fix does
not correct the condition, a new carburetor will have
to be installed.
(2) Install the accelerator pump discharge check
needle, jet housing and gasket. Install housing and
attaching screws. Tighten screws securely.
(3) Press down on the accelerator pump plunger
shaft, and as the plunger is being depressed, a clear
straight stream should emit from each jet. If the
streams are not identical, (if either one is diverted or
restricted) a new accelerator pump jet housing should
be installed. After test, pour the gasoline from the
carburetor bowl and remove pump plunger.
Assembling the Air
Horn
(1)
Slide the fuel inlet screen into the fuel line
fit-
ting, then install in air horn. Tighten securely.
(2) Check to see if the leather on the accelerator
pump plunger is hard, cracked or worn. If any sign
of wear or deterioration is evident, install a new
plunger assembly.
(3) When reassembling, make sure the large diam-
eter of the pivot screw enters the hole in the pump
arm and that the shoulder on the screw has not
pinched the pump arm.
The carburetors are equipped with synthetic rub-
ber tipped fuel inlet needles. The needle tip is a rub-
ber material which is not affected by gasoline and is
stable over a wide range of temperatures. The tip is
flexible enough to make a good seal on the needle
seat, and to give increased resistance to flooding.
The use of the new inlet needles requires that care
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