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14-20
CARBURETOR-BBS
m-
1
CLOSING PRESSURE
Fig. 1 &Fast
Idle Cam Position Adjustment
til the correct valve opening has been obtained. Refer
to
(Fig. 14).
Vacuum
Kick
Adjustment
(This test can be made
On
or
Off
the vehicle.)
The choke diaphragm adjustment controls the fuel
delivery while the engine is running. It positions the
choke valve within the air horn by action of the link-
age between the choke shaft and the diaphragm. The
diaphragm must be energized to measure the vacuum
kick adjustment. Use either a distributor test machine
with
a
vacuum source, or vacuum supplied by another
vehicle.
(1)
With the engine
Not
running, open the throttle
valves far enough to allow the choke valve to be
moved to the closed position.
(2)
Disconnect the vacuum hose from the dia-
phragm and connect the hose from the vacuum sup-
ply, as shown in (Fig.
15).
(A minimum of 10 inches of
mercury (HG) will be required.)
(3) Insert the specified drill
or gauge between the
choke valve and the wall of the air horn. Refer to
(Fig. 15). Apply sufficient closing pressure on the
choke shaft lever to provide the smallest choke valve
opening possible without distortion of the diaphragm
link. Note that the cylindrical stem of the diaphragm
will extend, as an internal spring is compressed. The
spring must be fully compressed for proper measure-
ment of the kick adjustment.
(4) An adjustment will be necessary if a slight drag
is not obtained as the drill or gauge is being removed.
The adjustment of this opening will require the re-
moval
of
the choke operating link.
AUGF
.EVER
-
Fig. IS-Vacuum
Kick Adjustment
CAUTION: Damage to the diaphragm and the
choke lever slot can result, if the link is not re-
moved for the bending operation.
(5) Remove the clip and disengage the choke oper-
ating link from the diaphragm stem, then disengage
the link from the choke lever. (The best bending
results will be obtained by using a vise and a pair of
pliers.)
(6) Bend the choke operating link at the angle to
provide the correct choke valve opening.
CAUTION: A correction in the length of the link of
.010
inch, will result in a change of
.015 inch in the
choke valve opening.
As an example, if the choke valve opening is 0.015
inch in error, the correction in the link length would
be .010 inch.
A
2
inch micrometer will be helpful in establishing
the original length of the link, as shown in (Fig. 16),
before completing the adjustment.
(7)
Install the choke operating link and recheck the
choke valve opening, using a gauge or drill. Refer to
(Fig. 15).
Reinstall the vacuum hose to the diaphragm and
NK652
Fig. 16-Choke
Operating Link Measurements
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