Chevrolet 1973 Overhaul Manual page 182

behind the fuel inlet nut to give maximum filtration of
incoming fuel.
An electrically operated idle stop solenoid is attached to
the carburetor float bowl casting and replaces the curb
idle speed screw. The idle stop solenoid is used in
conjunction with the combination emission control valve
(C.E.C. valve) L /D vehicles only. The idle stop solenoid,
energized when the ignition is turned on, controls the
engine curb idle speed. The C.E.C. valve, when energized
through the transmission, acts as a throttle stop by
maintaining a higher idle speed during high gear
opeartion of the egine, which helps in controlling
overrun emissions during deceleration. The C.E.C. valve
also provides full spark vacuum advance during high
gear operation and is de-energized in the lower gears
and at idle for retarded spark timing during this period.
The carburetor part number is stamped on a vertical
section of the float bowl, next to the fuel inlet nut. When
replacing the float bowl assembly, follow the manufac­
turer's instructions contained in the service package so
that the part number can be transferred to the new float
bowl.
The idle mixture screw will have a limiter cap installed
and no adjustment is provided on the vehicle. The
mixture screw will be pre- set at the factory and capped,
and no further adjustment should be required except
during the cleaning and overhaul.
An overhaul idle mixture adjustment procedure is
provided, should the idle mixture needle need replace­
ment or the mixture channels cleaned during the
overhaul process. A new idle mixture needle limiter cap
is provided in the overhaul kit.
Fig. M 2-Rochester Monojet Carburetor - L/D
Emission Carburetor
Shown (Typical)
DISASSEMBLY OF CARBURETOR
C.E.C. Valve Assembly and Idle Stop
Solenoid
Removal
1. Remove vacuum hose from the C.E.C. valve and
ported spark tube from throttle body (manual
transmission only).
2. Bend back retaining tabs on lock washer; then
remove large C.E.C. valve nut and remove valve
from bracket.
NOTE: Do not remove C.E.C. valve bracket
from the float bowl assembly unless replace­
ment is necessary.
3. Remove the electrically operated idle stop solenoid
wire connector, and unscrew the solenoid from the
float bowl casting by turning the solenoid body
counterclockwise.
CAUTION: Do not immerse the C.E.C. valve
assembly or Idle Stop Solenoid in any type of
carburetor cleaner.
Installation
Reverse Procedure:
NOTE: Be sure to bend tabs of lockwasher
over C.E.C. valve nut after securing to
bracket.
Air Horn
1. If desired, the choke valve, and choke shaft can be
removed from air horn by first removing the
thermostatic coil lever from the end of choke shaft
by removing attaching screw.
Remove the two choke valve attaching screws; then
remove the choke valve and choke shaft from air horn.
NOTE: The choke valve screws are held in
place by Loctite so it will be necessary to
restake or use Thread Lock No. 7041970 or
equivalent during assembly.
2. No further disassembly of the air horn is necessary.
The pressure relief valve disc need not be removed
from the top of the air horn for cleaning purposes.
Float Bowl
1. Remove air horn to float bowl gasket. Gasket is slit
next to metering rod hanger so that it can be easily
removed.
2. Remove float assembly from float bowl by lifting
upward on float hinge pin. Remove hinge pin from
float arm.
3. Remove float needle, float needle seat and gasket.
Use caution in removing needle seat to prevent
damage.
4. Remove fuel inlet nut, gasket, paper filter element
and pressure relief spring.
5. Using long nosed pliers, remove "T " pump
CARBURETORS 6 M - 3
OVERHAUL MANUAL