Ford COUGAR 1968 Shop Manual page 539

PART 1 0-6
-
Holley Model.
4 1 50
C
4-V
Carburetor
10-79
plates will approach wide open posi-
tion.
The bleed past the ball check valve
in the vacuum passage of the second-
ary diaphragm housing limits the rate
at which the secondary throttle plates
will open. Any rapid increases in vac-
uum, which would tend to open the
secondary throttle plates too suddenly,
merely holds the ball check valve se-
curely against its seat. The opening
of the throttle plates is slowed to a
rate governed by the amount of air
passing through an air bleed in the
ball check valve seat. This allows the
vacuum to build up slowly at the dia-
phragm, which results in a controlled
rate of opening for the secondary
throttle plates.
When engine speed is reduced, ven-
turi vacuum in the bores becomes
weaker. The momentarily stronger
vacuum at the secondary throttle op-
erating diaphragm moves the ball
check valve off its seat in the vac-
uum passage, permitting an immedi-
ate flow of air into the diaphragm
chamber. As the vacuum acting on
the diaphragm is lessened, the load on
the diaphragm spring will start closing
the secondary throttle plates. The dia-
phragm spring is assisted by the de-
sign of the secondary plates. Each
secondary plate is slightly off set.
When the plates are closing, the com-
bined force of manifold vacuum and
the air stream has greater effect on
the larger, upstream area of the
plates, forcing them to a closed posi-
tion. The secondary plates a r e retain-
ed in the closed position when pri-
mary plates are fully closed by the
.
.
2 REMOVAL A N D INSTALLATION
Flooding, stumble on acceleration,
and other performance complaints are,
in many instances, caused by the
presence of dirt, water, or other for-
eign matter in the carburetor. To aid
in diagnosing the cause of a com-
plaint, the carburetor should be care-
fully removed from the engine with-
out removing the fuel from the.bowls.
The contents of the bowl may then
be examined for contamination as the
carburetor is disassembled.
REMOVAL
1. Remove the air cleaner. Remove
the throttle rod from the throttle lever.
Disconnect the choke control heat
tube and the fuel line at the carburetor.
2. Remove the carburetor retain-
ing nuts and lockwashers; then re-
move the carburetor and mounting
gasket. Remove the carburetor spac-
er and gaskets. Discard the gaskets.
INSTALLATION
1. Be sure all old gasket material
is removed from the spacer. Install a
new lower spacer gasket and the spac-
er on the intake manifold. Position the
3 M A J O R REPAIR OPERATIONS
DISASSEMBLY
To facilitate working on the carbu-
retor(~), and to prevent damage to the
throttle plates, install carburetor legs
on the base. If the legs are unavail-
able, install four bolts, about 2 114 in-
ches long of the correct diameter, and
eight nuts on the carburetor base.
Use a separate container for the
component parts of the various as-
semblies, to facilitate cleaning, inspec-
tion, and assembly.
The following is a step-by-step se-
quence of operations for completely
overhauling the carburetor. However,
certain components of the carburetor
may be serviced without a complete
disassembly of the entire unit. For a
complete carburetor overhaul, follow
all the steps. T o partially overhaul the
carburetor or to install a new gasket
kit, follow only the applicable steps.
Refer to Fig. 18 for identification
of the parts used on the Holley car-
buretor.
P R I M A R Y FUEL BOWL AND
METERING BLOCK
I. Disconnect the inter-connecting
fuel line a t the primary and secondary
fuel bowls. Remove the retaining
screws and gaskets, fuel bowl and
secondary throttle connecting rod.
This rod, which is fastened to the pri-
mary throttle lever, rides in a slot in
the secondary throttle lever.
A transfer slot or passage begins
to function when the secondary throt-
tle plates begin to open. As the plates
begin to open, the fuel flows through
the main metering restrictions into
the transfer passages. which are simi-
lar to those in the primary metering
block.
When the secondary throttle plates
are opened further, the difference in
pressure between the secondary boost-
er venturis and the secondary fuel
bowl causes the secondary main fuel
system to begin discharging fuel. The
passages in this system are similar
to those in the primary main fuel sys-
tem.
carburetor and a new gasket on the
spacer.
Connect the choke heat tube, and
fuel'inlet line loosely to the carburetor.
Install the carburetor retaining lock
washers and nuts. Tighten the nuts
evenly and alternately.
2. Tighten the choke heat tube and
fuel line fittings at the carburetor.
Connect the throttle rod. Refer to
Common Adjustments and Repairs
and adjust the engine idle speed, idle
fuel mixture, fast idle speed and the
anti-stall dashpot (if so equipped).
Install theair cleaner.
gasket and the metering block and
gasket. Discard the gaskets. Remove
the baffle.
2. Remove the idle adjusting
screws from the metering block.
3. Using a jet wrench, remove the
main jets (Fig. 1 I).
4. Using a socket wrench, remove
the power valve and gasket (Fig. 12).
5. Remove the fuel level adjust-
ment lock screw and gasket. Turn the
adjustment nut counterclockwise and
remove the lock nut and gasket. Re-
move the fuel inlet needle and seat
assembly. Do not disassemble the fuel
inlet needle and seat. They are match-
ed assemblies and are replaced as an