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Below governing speeds, the operator,
through
a simple clutch arrangement on the
throttle body
of the carburetor, controls the throttle
plates in
the usual manner. When governing
speed is reach
ed, a combination of venturs. and
manifold vacuum
acts on the governor diaphragm to
close the throt
tle plates. Two calibrated by-pass
jets in the
vacuum passages meter the vacuum
from the
venturi and the manifold to provide
the correct
balance for proper operation of
the governor. At
speeds below governing rpm, this
vacuum is weak
ened by air bleeding through the
governor valve so
Gnat no premature governing action
will occur.
Filtered air from the carburetor
air cleaner enters
the governor system through the
governor vent
tube. The air flows through an air
line to the
housing enclosing the governor rotor.
Governor
vacuum draws the air past the governor
valve and
through another air line to the
throttle actuating
unit on the carburetor. In the controlling
unit in
the distributor, centrifugal force
acting on the
rotor, which has kept pace with
engine speed,
overcomes the tension of the valve
spring and
tends to close the governor valve
when governing
speed is reached. This greatly restricts
the amount
of air bleeding through to the diaphragm
on the
and manifold vacuum to operate the
diaphragm.
As the vacuum acting on the diaphragm
increases,
the diaphragm moves the governor
lever against
the tension of the governor spring
to close the
throttle plates. The governed engine
speed is
held constant by centrifugal force
on the valve
balanced against the tension of
the valve spring.
Any slight change in engine speed
will cause the
governor valve to act immediately
to either in
crease or decrease the amount of
air bleeding
through the governor valve orifice.
A change in
the amount of air bleed will, in
turn, cause an
instant response from the diaphragm
to increase
or decrease the throttle plate opening.
When the
accelerator is released, control
is taken from the
governor by the external throttle
lever and the
return spring in the accelerator
pedal linkage
closes the throttle plates to bring
the engine to
any desired lower speed.
Although the entire governor system
is de
scribed, only the throttle actuating
mechanism on
the carburetor is included in the
overhaul pro
cedure presented in this manual.
The governor
can be cleaned and serviced with
ordinary tools
and the governor rotor can be serviced
independ
ently.
OVERHAUL
1. INTRODUCTION
The overhaul procedure which follows
can be
accomplished with ordinary tools
and a reasonable
amount of care. However, factory
approved tools
are available to facilitate overhaul
and protect
parts which might be damaged by
ordinary tools.
Use of these tools is strongly
recommended.
Proper overhaul of a carburetor
can only be
accomplished if the unit is completely
disassembled
and each part is thoroughly cleaned.
The clean
parts should then be carefully
inspected for signs
of wear, damage or deterioration.
Any parts which
are defective must be replaced
only with genuine
Holley replacement parts. The carburetor
must
then be carefully rebuilt and accurately
adjusted to
insure the power, economy and performance
which
is built into every Holley Carburetor.
Z. SPECIAL TOOLS
The special tools recommended for
use in overhauling this carburetor are listed below.
Main Jet Socket . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inlet Plug Remover . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Inlet Valve Seat Socket .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Valve Socket . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Snap Ring Hook . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Economizer Socket . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(used for spark valve adapter body
screw)
Governor Diaphragm Positioning
Tool . . . . . . . . . . . . . . . . . . . . . . . .
Float Gauge . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Float Lever Bending Tool .,. .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Snap-On Tool No. TMC-36
Snap-On Tool No. TMC-38
Snap-On Tool No.
MC-
125
Snap-On Tool No.
MC-
127
Snap-On Tool No.
MC-
141
Snap-On Tool No.
MC-
