Ford COUGAR 1968 Shop Manual page 537

PART 10-6
-
Holley Model
41 50 C 4-V
Carburetor
1 0-77
MAlN
AIR B
FIG.
&-Typical Holley
4-V
Primary Stage Main Fuel System
MAlN F
DISCHARGE
MAlN WELl
AIR BLEEl
sage, the fuel-air mixture flows
through a short passagein the main
body, and down another passage into
the throttle body. The fuel is discharg-
ed below the closed throttle plate.
A transfer slot acts as an air bleed
at idle. The secondary idle fuel system
continues discharging fuel until the
secondary main fuel system comes in-
to operation.
ACCELERA'I'ING SYSTEM
The accelerating system for the
primary and secondary carburetors
operate in the same manner; there-
fore, only one carburetor is discussed.
Upon acceleration, the air flow
through the carburetor responds al-
most immediately to the increased
throttle opening. There is, however, a
brief interval before the fuel, which
is heavier than air, can gain speed and
maintain the desired balance of fuel
and air. During this interval, the ac-
celerating pump supplies fuel until
the other fuel systems can once again
provide the proper mixture (Fig.
7).
The accelerating pump is located
in the bottom of the primary fuel
bowl. It begins to function when the
pump operating lever is actuated by
throttle movement. When the throttle
is opened, the accelerating pump link-
age, actuated by a cam on the pri-
mary throttle shaft, forces the pump
diaphragm up. As the diaphragm
moves up, the inlet ball check is
forced onto its seat, preventing fuel
from flowing back into the fuel bowl.
The fuel flows from the short pas-
sage in the primary fuel bowl into
the long diagonal passage in the .pri-
mary metering block.. The fuel passes
into the main body and then into the
pump discharge chamber. The pres-
sure of the fuel raises the discharge
needle and fuel is discharged into the
venturi from the pump nozzle.
As the throttle is moved toward
the closed position, the linkage returns
to its original position and the dia-
phragm spring forces the diaphragm
down. As the diaphragm returns to
its original position, the pump in.let
ball check is moved off its seat and
the diaphragm chamber is filled with
fuel from the fuel bowl.
PRIMARY STAGE M A l N
FUEL SYSTEM
MAIN.JET MAIN WELL
-
~ 1 4 0 7 . 8
FIG.
9-Typical Holley
4-V
Power Fuel System
The primary stage main fuel sys-
tem for the primary and secondary
carburetors operate in the same man-
fuel passage, the fuel-air mixture sage and then down another vertical ner, therefore, only one carburetor is
flows through a short horizontal pas- passage. At the bottom of this pas-
discussed.