Advertisement
(101)
ENGINE FUEL AND EXHAUST SYSTEMS
CARTER CARBURETOR
3-27
the cranking motor control circuit, is incorpo-
rated in the throttle body flange of carburetor.
Air enters both barrels of carburetor through
the air horn which has one inlet and contains
the choker valve. Fuel is supplied to both bar-
rels from one float chamber. The float chamber
encircles both barrels and contains a dual type
float and lever assembly which operates one
float needle or valve. The accelerating pump jet
in each barrel is supplied with fuel from one
pump located in the float chamber. The power
systems of both barrels are controlled by
one·
vacuum piston and link.
Except as noted above, each barrel forms a
complete carburetor system. Each barrel con-
··
tains a low speed system with an adjustment
screw, a high speed system with a metering
rod, accelerating pump discharge jet, a triple
venturi system, and a throttle valve. The throt-
tle valves of both barrels are mounted in line
on one shaft. The dual construction combines
the advantages of two carburetors in one
com-
pact
unit.
The dual carburetor and dual intake
manifold provide more uniform distribution of
fuel to all cylinders than would be possible with
one single barrel carburetor.
Operation of each system of the WCD Carter
carburetor is described in the following sub-
paragraphs. The climatic control is described
in paragraph 3-22, which follows. The accel-
erator vacuum switch is described in para-
graph 10-32.
Fig.
3-33-Float System-Carter Carburetor
b. Operation of Carter Float System
Fuel enters the carburetor at the gasoline
connection and flows through the strainer and
needle seat into the float chamber. When the
fuel reaches the prescribed level in float cham-
ber, the dual float presses the needle
against
its seat to shut off the flow of fuel. Thereafter,
the fuel is maintained at the prescribed level
by opening and closing of needle as
required.
The float lever is hinged on a pin and connected
to the float needle by a clip. The float chamber
is vented externally through a port in air horn
to allow fuel to be smoothly withdrawn through
the various systems. See figure 3-33.
Fig.
3-34-Low Speed
System-Ca rter
Carburetor
c. Operation of Carter Low Speed or
Idle System
Fuel is delivered to the egine through the low
speed system at closed throttle and light load
speeds up to approximately 20
MPH.
The low
speed system also partially controls fuel supply
for light load speeds up to approximately 30
MPH.
The operation of the low speed system in
each barrel of the carburetor is identical. Fuel
flows from the float chamber through the me-
tering rod jet into a passage which supplies
both the low speed jet and the main nozzle. It
then flows upward through the low
speed
jet
which
meters
the fuel
used by t
he low speed
system.
At the upper end of the low
speed jet
t
he
fuel is combined
with
a
st r eam of air com-
ing in f
rom the
carburetor throat through a
by-pass. The combining of the air stream with
the fuel tends to atomize or break up the gaso-
line into a
vapor.
See figure 3-34.
The fuel-air mixture passes through a small
drilled passage called the economizer and is
combined with an additional air stream coming
Advertisement
