Chevrolet Light Duty Truck 1973 Service Manual page 450

6 M - 2 6 E N G IN E FUEL
5. Install bolt and tighten securely.
. Adjust and connect choke rod as outlined.
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7. Start and warm-up the engine then check operation
of choke and install air cleaner.
V8 Engines (Figs. K2-K3)
1. Remove air cleaner and disconnect choke rod upper
clip.
2. Remove choke coil as follows:
WITH ROCHESTER
CARBURETORS
Remove the choke coil shield by prying with a screw
driver on the small tangs at base of shield, then lift
shield carefully over rod.
Remove choke rod, bracket screw and choke coil
assembly.
3. Install a new choke coil assembly being sure the
locator is in the hole of the intake manifold and
install mounting screw.
4. Complete installation as follows:
WITH ROCHESTER
CARBURETORS
Install the choke rod and adjust as necessary (without
choke coil shield installed).
Disconnect choke rod upper end and lower choke coil
shield over choke rod and install over choke coil.
5. Be sure choke valve moves freely from full open to
full closed position.
. Start and warm up the engine and check operation
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of the choke.
7. Install the air cleaner.
ON-THE-VEHICLE ADJUSTMENTS
Final curb idle and fast idle settings should be made on
the vehicle using a tachometer. All idle speeds in 1973
are to be set with the air conditioning in the OFF
position unless otherwise indicated. Idle speed and
mixture settings must be made with the air cleaner
installed. Warm engine to normal operating tem pera­
ture, choke valve and thermostatic air cleaner valve must
be in full open positions. Idle settings must follow
procedure shown on the, "Vehicle Emission Control
Inform ation" sticker, sometimes referred to as tuneup
sticker.
ADDITIONAL EXTERNAL
SETTINGS AND ADJUSTMENTS
All Vehicles
After carburetor overhaul, throttle body part replace­
ment, mixture needle part replacement, or limiter cap
and needle removal for any reason, the below procedures
must be followed:
1. Refer to Vehicle Emission Control Information
4MV AND 2GV
4MV AND 2GV
Sticker, sometimes referred to as tuneup sticker,
(also see Section , Tuneup) before proceeding:
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CAUTION: After following the below proce­
dure, always double check and s e t specifications
which agree with l a t e s t c e r t i f i e d information on
Vehicle Emission Control (tuneup) Information
s t i c k e r .
2. Turn mixture screw in until it lightly
contacts seat, then back screws out four
(4) full turns.
3. Adjust idle stop solenoid or carburetor
speed screw to obtain, "initial curb idle
speed", see "Other Adjustments" Speci­
fications chart in back of this M anual -
Column No. 1.
4. Adjust mixture screw as follows:
a. Adjust mixture screws equally (in) to idle speed
specified by specifications in Column No. 2.
b. When 1/4 turn rich from lean roll is specified,
turn mixture screw equally (in) leaner to a drop
of 20 RPM then turn mixture screw 1/4 turn
rich (out). Set final idle speed to RMP under
"Other Adjustments" in Specifications chart in
back of this Section - Column No. 2.
5. Install service "M ixture Needle Limiter Caps"
on mixture screws.
. Reconnect distributor vacuum hose and fuel
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tank vapor hose.
IDLE STOP SOLENOID
(CURB IDLE-LOW IDLE) ADJUSTMENT
With engine at normal operating temperature, air
cleaner installed, choke open, and air conditioning off, if
so equipped.
CAUTION: Set parking brakes and block the
drive wheels.
1. Disconnect fuel tank hose vapor canister.
2. Disconnect distributor vacuum hose at the distrib­
utor. Plug hose lead-to carburetor.
3. With engine running;
ONE BARREL CARBURETORS
CAUTION: During adjustment, do not turn the
solenoid more than one complete turn without
f i r s t disconnecting the e l e ctric al wiring.
a. Turn the solenoid clockwise to increase RPM,
counterclockwise to decrease RPM. Refer to
Specifications, Section
justments", column No. 2, for curb idle speed
(Idle Stop Solenoid-Energized).
b. Set low idle speed (with solenoid de-energized)
to 450 RPM by using an alien head wrench
(located at the end of this solenoid). Turn to
adjust.
M, under "O ther Ad­
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LIGHT DUTY TRUCK SERVICE MANUAL