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3-42
STROMBERG CARBURETOR
ENGINE
FUEL AND
EXHAUST SYSTEMS
(116)
system,
accelerating
system, and automatic
choke. An accelerator vacuum switch, which is
part of the cranking motor control circuit, is
incorporated in the carburetor assembly.
Air is supplied to both barrels of carburetor
through the air horn which has one inlet and
contains the choke valve. Fuel is supplied to
both barrels from one float chamber. The float
chamber encircles both barrels and contains a
dual type float and lever assembly which actu-
ates one float needle valve. The accelerating
pump discharge nozzle in each barrel is sup-
plied with fuel from one pump located in the
float chamber. The power system for both bar-
rels is controlled by one vacuum power piston.
Except as noted above, each barrel forms a
complete carburetor system. Each barrel con-
tains an idle system with adjustable needle
valve, a main metering system, accelerating
pump discharge nozzle, primary and auxiliary
venturi tubes, and a throttle valve. The throttle
valves of both barrels are mounted in line on
one stem. The dual construction provides the
advantages of two carburetors in one compact
unit. The dual carburetor and dual intake mani-
fold provides more uniform distribution of fuel
to all cylinders than would be possible with one
single barrel
carburetor.
Operation of each system of the AA V Strom-
berg carburetor is described in the following
subparagraphs. The automatic choke is de-
scribed in paragraph 3-29, which follows. The
accelerator vacuum switch is described in para-
graph 10-33.
CONNECTION
SEAT
VALVE
PIN
CHAMBER
Figur
e 3-63-Float System -Stromberg
Carburetor
b.
O
pe ration
of
Stromberg Float System
Fuel enters the carburetor at the gasoline
connection
and flows through the strainer and
needle valve seat into the
float
chamber. When
the fuel reaches the prescribed level in float
chamber, the dual float presses the needle valve
against its seat to shut off the flow of fuel.
Thereafter, the fuel is maintained at the pre-
scribed level by opening and closing of the
needle valve as required. The float lever is
hinged on a fulcrum pin and conn
ected
to the
needle valve by a clip. See figure
3-63.
The float chamber is
vented
ext er n a ll y
through a port in air horn to allow fuel to be
smoothly withdrawn through the various sys-
tems.
Figure 3-64-ldle System-Stromberg Carburetor
c.
Operation
of Stromberg Idle (Low
'
Speed)
System
Fuel is delivered to
the
engin e th r ough the
idle system at closed throttle and light load
speeds up to approximately 20
MPH.
The idle
system also partially controls fuel supply for
light load speeds up to approximately 30 MPH
.
The operation of the idle system in each bar-
rel of the carburetor is
identical.
Fuel flows
from the float chamber through main metering
jet and upward through the idle tube which
meters
the fu
el.
From the idle
tube
it flows
through a connecting channel where air from
the
idle air bleeder is mixed with it so that a
mixture of air and fuel passes down the idle
channel to the idle discharge
holes.
Additional
air is drawn into the fuel air mixture in the
idle channel through the secondary air bleeder.
See figure
3-64.
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