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14-30
CARBURETOR-BBD
1
' / a
INCH
and 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.
16).
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 temperature.
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.
Choke Unloaded (Wide Open Kick)
(1)
Hold the throttle valves in the wide open posi-
tion. Insert Tool T109-31 or
Y,"
drill shank between
the upper edge of the choke valve and the inner wall
of the air horn, as shown in (Fig. 1 7 ) .
(2)
If no drag is felt, or if too much drag is appar-
ent, bend the unloader tang on the throttle lever, un-
til correct clearance has been obtained.
Idle Speed Adjustment (Curb Idle)
To make the idle speed adjustment, the engine
must be thoroughly warmed up. A much more reliable
idle adjustment can usually be obtained if the car has
been driven a minimum of five miles. For the best re-
sults, it is recommended that a tachometer be used
in this adjustment. (Before making the idle speed ad-
justment, 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 (high beam). This will assure setting the
idle to compensate for the alternator load. On vehi-
cles equipped with the automatic transmission, dis-
connect the transmission control rod from the ball
joint on the carburetor lever so that the stop in the
transmission will not interfere with the free move-
ment of the carburetor throttle lever.
(1)
Turn the idle speed screw
in
or
out
to obtain
500
r.p.m. (On cars with air conditioning, set the idle
speed at
500
r.p.m., with air conditioning
On.)
Be sure
that the choke valve is fully open and that the fast
idle adjusting screw is not contacting the fast idle
cam.
(2)
Turn each idle mixture screw to obtain the high-
est r.p.m. While making the adjustment, watch the
tachometer and notice that the speed can be de-
creased by turning the screws in either direction from
+he setting that gave the highest r.p.m. reading.
LIGHT CLOSING
DRILL
O R GAUGE
Fig. 17-Measuring
the Choke Unloader Setting
(3) Readjust to 500 r.p.m. with the idle speed
screw.
(4)
Turn
each idle mixture adjusting screw in the
clockwise direction (leaner) until there is a slight drop
in r.p.m. Now, turn each screw out counter-clockwise
(richer) just enough to regain the lost r.p.m.
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 lean-
est smooth idle setting will probably be too fast.
(5) Readjust the speed screw
to
obtain correct idle
THE SLOWEST SPEED STEP OF THE
I'
FAST IDLE CAM
Fig. 18-Fast
Idle Speed Adjustment
lon
the vehicle)
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