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14-48
CARBURETOR-WW3
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
results,
it
is recommended that a tachometer be used
in this adjustment. (Before making the idle speed
adjustment observe the following precautions):
Because the alternator can change 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 lever.
To make the idle speed adjustment, proceed as fol-
lows:
(1) Turn the idle speed screw in or out to obtain
500
r.p.m. (With air conditioning
On,
set the idle speed
at
500
r.p.m.). Be sure the choke valve
is
fully open
and the fast idle adjusting screw is not contacting the
fast idle cam.
(2)
Turn each idle mixture screw to obtain the
highest 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
the setting that gave the highest r.p.m. reading.
(3) Readjust to
500
with the idler 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, counterclock-
wise (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
speed. Repeat steps
2
and
4
above if necessary.
After the proper idle speed has been obtained, re-
FAST IDLE SPEED ADJUSTING
SCREW
O N
THE SLOWEST
USPEED
STEP ON THE CAM
SCREW
Fig. 24-Fast
Idle Speed
(on
the Vehicle1
fer to (Fig. 3), in the Throttle Linkage Section of this
Group for the procedure on adjusting the transmis-
sion control rod.
Fast Idle Speed
Ion
the Vehicle After
Approximately
500
miles
if
requiredl
To set the fast idle speed on the car, connect a ta-
chometer, 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.
(3) The fast idle speed adjusting screw should be
contacting the slowest speed step on the fast idle cam,
as shown in (Fig.
24).
(4)
With the engine warmed-up to the normal oper-
ating temperature, turn the fast idle speed adjusting
screw
in
or
out
to secure
700
r.p.m.
Reposition the
cam and throttle after every screw adjustment, to ap-
ply normal throttle closing torque.
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