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14-1 2
CARBURETOR-HOLEY
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
.010
inch in
the choke valve opening.
As an example, if the choke valve opening is .010
inch in error, the correction in the link length would
be .010 inch.
A "1" inch micrometer will be helpful in establish-
ing the original length of the link, as shown in Figure
13, before completing the adjustment.
(7)
Install the choke operating link and recheck
the choke valve opening, using a gauge or drill. Refer
to (Fig. 12).
Reinstall the vacuum hose to the diaphragm fitting
and make the following check:
(8)
With no vacuum applied to the diaphragm,
some clearance should exist between the choke oper-
ating link and the choke lever slot, in both the open
and closed choke valve positions, as shown in (Fig.
14).
This clearance is necessary to allow the choke
valve to close for starting as well as fully open, after
the engine reaches the normal operating tempera-
ture.
If a clearance does not exist in both of these posi:
tions, a recheck .of the operating link adjustment
should be made.
Free movement of the choke valve between the
closed and open positions is very necessary.
This free movement should also exist between the
kick and the open choke valve positions with the en-
gine running. If binding does exist, the choke operat-
ing link has been improperly bent and should be cor-
rected.
Idle Speed (On the VehicleJ*
To make the idle speed adjustment, the engine
must be thoroughly warmed up. A much more reli-
able idle adjustment can usually be obtained if the
car has been driven a minimum of five miles. For the
best results, it is recommended that tachometer be
used in this adjustment. (Before making the
idle
speed adjustment, observe the following precautions.)
Because the alternator can charge at idle speeds
and impose a load on the engine, the headlights
should be turned on. This will assure setting the idle
to compensate for the alternator load. On cars
equipped with automatic transmissions, unsnap the
ball joint connection at the accelerator shaft bell
crank. If this is not done, it is possible that the car-
buretor throttle will be held open against the stop
in the transmission. The carburetor would therefore
not respond to adjustment of the idle speed screw.
After the proper idle speed has been obtained at the
carburetor, screw the ball joint connector up or down
until the ball on the bell crank will exactly mate with
the socket. Snap into place.
To make the idle speed adjustment, proceed as fol-
lows:
(1) Turn the idle speed screw
in
or
out
to obtain
550
r.p.m. (Be sure that the choke valve is fully open
and that the fast idle adjusting screw is not contact-
ing the cam.)
(2)
Adjust the idle mixture screw to obtain the
highest r.p.m. While making the adjustment, careful-
ly watch the tachometer and notice that the speed
can be decreased by turning the screw in either di-
rection from the setting that gave the highest r.p.m.
reading.
(3) From the highest idle speed setting, turn the
mixture screw clockwise (leaner) until the speed starts
to drop. Turn the screw in the opposite direction
(counter-clockwise) just far enough to recover the
speed that was lost.
This procedure will assure that the idle has been
set to the leanest mixture possible for smooth idle.
This setting is very important.
Since the correct speed was originally set using the
speed screw, the speed obtained after finding the
leanest smooth idle setting will probably be too fast.
(4)
Readjust the speed screw to obtain correct idle
speed. Repeat steps 2 and 3 above.
Fast Idle Speed Adjustment (On the
Cad*
To set the fast idle speed on
the
car, connect a
tachometer to the vehicle, then set the curb idle
speed and proceed as follows:
(1) With the engine running and the transmission
in the neutral position, open the throttle slightly.
(2) Close the choke valve about 20 degrees then
allow the throttle to close. Return the choke valve to
the open position.
FAS'
ADJ
ON
SPEED STEP OF
THE
SCI;
T IDLE SPEED
CHOKE VALVE
USTING SCREW
THE SLOWEST
Fig. IS-Fast
Idle Speed Adjustment ton the vehicle1
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