Hudson 63 1936, Mechanical Procedure Manual

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SECTION 4
Page 6
MECHANICAL PROCEDURE MANUAL
To prevent this action, which is known as percolation, an
anti-percolating valve, Figure 404, is incorporated in the
carburetor.
The valve opens and closes a vent which connects directly
at the bottom of the main nozzle and carries off any vapor
bubbles which may form so that gasoline is not forced out
of the nozzle.
The valve is opened by the throttle linkage when the
throttle closes to the idling position and closes with the
slightest opening of the throttle.
Slow Closing Throttle
When driving at high speeds with open throttle there is a
rapid flow of gasoline through the carburetor. If the throttle
is suddenly closed, cutting off the flow-of air to the engine,
the gasoline will continue flowing due to its inertia and
result in a momentary rich mixture which may cause the
engine to run unevenly or even stall.
By preventing the throttle from closing rapidly when
pressure is released from the accelerator pedal, this gasoline
is used without causing uneven running of the engine.
Slow closing of the throttle is accomplished by the use of
a plunger operating in a cylinder in the carburetor float
chamber (Figure 405). As the throttle is opened the plunger
moves upward and gasoline passes check ball valve in the
stem of the plunger and also through the small hole in the
stem just below the check valve, filling the cylinder below
the plunger full of gasoline. When the pressure is relieved
from the accelerator pedal, the throttle spring attempts to
close the throttle, however, the check ball goes to its seat and
the speed of closing of the throttle is retarded as the gasoline
below the plunger can escape only through the small hole in
the plunger stem.
Climatic Control
The climatic control is an integral part of the carburetor and
consists primarily of two major assemblies: the thermostatic
coil and the piston plate housing assembly. The thermostatic
coil assembly consists of cover, insulators and thermostatic
coil (Figure 407).
The housing assembly consists of the piston plate housing
(R), choke shaft lever (J), screen (P) and piston (K).
The operation of the climatic control depends on intake
manifold vacuum and exhaust manifold heat.
On initial starting, as the engine fires, the vacuum created
in the intake manifold tends to pull the piston (K) down,
exerting tension on the thermostatic coil and opening the
choke valve far enough for initial running. Hot air is drawn
through the stove on the exhaust manifold, through the
connecting pipe and entering the housing through the screen,
and passing around the piston to the intake manifold. As the
heat