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CARBURETOR-W W3
1 4 4 5
against seat. Engage pump shaft with pump arm and
secure with clip.
(4)
Install the vacuum power piston and plunger in
the air horn, as shown in (Fig. 16). Lock in position by
prick punching on the retaining rim. Compress the
piston plunger to be sure no binding exists. If the pis-
ton sticks or binds enough to hinder smooth opera-
tion, install a new piston assembly.
(5) Slide a new air horn gasket over accelerator
pump plunger, and down against air horn. Now, lower
air horn straight down on main body, with the ac-
celerator pump plunger sliding into its well. (Be sure
the leather on the pump does not curl or fold back.)
Install air horn retaining screws and lockwashers, then
tighten securely.
(6) Install the accelerator pump and fast idle con-
nector rods, then work the accelerator pump plunger
several times, to be sure
it
operates freely.
Choke Vacuum Diaphragm
Inspect the vacuum diaphragm fitting to insure that
the passage is not plugged with foreign material. Leak
check the diaphragm to determine if
it
has internal
leaks. To do this, first depress the diaphragm stem.
Then place a finger over the vacuum fitting to seal the
opening. Release the diaphragm stem. If the stem
moves more than
'Ilo
inch in 10 seconds, the leakage
is excessive and the assembly must be replaced.
(1)
Assemble to the air horn and tighten the at-
taching screws securely.
(2)
Install the choke operating link in position be-
tween the diaphragm plunger (stem) and the choke le-
ver. Install the clip to secure.
(3) Inspect the rubber hose for cracks before plac-
ing
it
on the correct carburetor fitting. Refer to (Fig.
1).
Do not connect the vacuum hose to the diaphragm
fitting until after the vacuum kick adjustment has
been made. (See Carburetor Adjustments.)
ADJUSTMENTS
It is very important that the following adjustments
be made on a reconditioned carburetor and in the
se-
quence listed, namely,
Cam Position Adjustment
Vacuum Kick Adjustment
Unloader Adjustment (wide open kick)
Accelerator Pump Travel Adjustment
Fast Idle Speed
Fust Idle Speed and Cam Position Adjustment
The fast idle engine speed adjustment should be
made on the vehicle, as described in the Fast Idle
Speed Adjustment (On the Vehicle) Paragraph. How-
ever, the Fast Idle Cam Position Adjustment can be
FAST IDLE SPEED ADJUSTING
SCREW ON SECOND STEP AND
AGAINST FACE
OF HIGHEST
STEP
OF
FAST IDLE CAM
CLOSING PRESSURE APPLIED
AGAINST CHOKE VALVE
BEND FAST IDLE R
AT ANGLE TO AD
FAST IDLE CAM
CAM
Fig. 17-Fast
Idle Cam Position Adjustment
made on the bench. This adjustment is important
to assure that the speeds of each cam step occur at
the proper time during engine warm-up. Adjust as
follows:
(1)
With the fast idle speed adjusting screw con-
tacting the step on the fast idle cam, shown in (Fig.
17), move the choke valve toward the closed position
with light pressure. Insert a
9/lo4
inch drill or gauge
between the choke valve and the wall of the air horn.
(2) An adjustment will be necessary if a slight drag
is not obtained as the drill or gauge is being removed.
(3) If an adjustment is necessary, bend the fast idle
\?
~
/DRILL
O R GAUGE
DIAPHRAGM S1
CLOSING PRESSURE
APPLIED ON CHOKE
' E M
VACUUM
CLIP
:HOKE OPERATING LINK
NK449
Fig. 18-Measuring
the Choke Vacuum Kick Setting
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