Ford LRG-423 Service Manual page 136

ZENITH MODEL #33 CARBURETOR OPERATION AND SERVICE (Continued)
When the throttle plate is opened to a point just above
the idle position, enough air passes through the
carburetor to lower the pressure at the discharge tube.
The float chamber is open to atmospheric pressure;
consequently, the greater pressure in the float
chamber will cause the fuel to flow from the fuel bowl
through the main jet into the main well and well tube.
Auxiliary Systems
WELL VENT
MAIN SYSTEM
Air admitted through bleed holes in the well tube, an
amount measured by the well vent, is mixed with the
fuel. This mixture of fuel from the main well tube
passes through the discharge tube in the venturi and
is added to the air stream in the venturi. This mixture
then passes into the intake manifold.
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