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ENGINE FUEL AND EXHAUST SYSTEMS
CARTER CARBURETOR
3-29
e.
Operation of Carter Power System
For maximum power or high speed operation
above approximately 75 MPH, a richer mix-
ture is required than that necessary for normal
throttle
opening.
The richer mixture is sup-
plied through the high speed systems of both
barrels of carburetor by means of the power
system.
The power system consists of a vacuum pis-
ton located in a cylinder connected to manifold
vacuum, a spring which tends to push the
piston upward against manifold vacuum, and a
vacumeter piston link attached to the piston
and supporting the two metering
rods.
See
figure
3-35.
Under part throttle operation, manifold
vacuum is sufficient to hold the piston and link
down against the tension of the spring, so that
the link is held against the tongue of the meter-
ing rod arm. The metering rods are then raised
and lowered mechanically as the throttle valve
is opened and closed. When the throttle valve is
opened to a point where additional fuel is
required for satisfactory operation, manifold
vacuum decreases sufficiently so that the piston
spring moves the piston, link and metering rods
upward to the proper metering rod step posi-
tion to give the required richer mixture, inde-
pendently of throttle opening. As soon as the
demand is passed, manifold vacuum moves the
piston link down against the metering rod arm
so that the metering rods are controlled
mechanically again.
'FI'I''''''-~~ CHECK
PLUG
PUMP
SPRING
~~~
,INTAKE
BAll
------
Fig .
3-36-Accelerating System-664S Carter
Carburetor
ISeries 70)
f. Operation of Carter Accelerating
System
The accelerating system supplies the extra
quantity of fuel which is needed momentarily
for smooth and rapid acceleration when the
throttle valve is suddenly opened.
A pump plunger, located in a cylinder ex-
tending into the float chamber, is
mechani-
cally operated from the throttle valve shaft by
means of the throttle shaft arm, throttle con-
nector rod, pump operating arm and counter-
shaft assembly, pump arm and pump arm
link.
The pump cylinder contains intake and
dis-
charge check valves and a
discharge
passage
leading to a pump
j
et in each barrel of
carbure-
tor. See figure 3-36
.
When the throttle is closed, the pump plunger
moves up and draws a supply of fuel from the
float chamber past the intake ball into the pump
cylinder.
When the throttle is opened, the pump
plunger on its downward stroke exerts pres-
sure on the fuel which presses the intake ball
against its seat, raises the check needle off the
discharge check
plug,
and discharges a metered
quantity of fuel through the pump jets into
each barrel of carburetor. This occurs only
momentarily during the accelerating
period.
The pump plunger spring provides a follow-up
action so that the fuel discharge carries out
over a brief period of
time.
See figure 3-36
.
In
the 664 S (Series 70) carburetor only, a relief
valve in the pump discharge passage plug pre-
vents excessive build-up of pressure in the
accelerating system when the throttle is sud-
denly snapped
open.
When the desired speed is reached and the
throttle is held in fixed position, the pressure
on the fuel in pump cylinder decreases
suffi-
ciently so that fuel ceases to discharge from the
pump jets. With the throttle held in a fixed posi-
tion the fuel flows only through the low speed
or high speed systems as previously described.
3-22 DESCRIPTION AND OPERATION
OF CARTER CLIMATIC CONTROL
(AUTOMATIC
CHOKE)
a
. General
Description
The climatic control consists of a choker valve
mounted on a shaft in the carburetor air horn,
a bi-metal thermostatic coil and housing
at-
tached to a housing cast on air horn, a vacuum
a~tuated
choke piston located in a cylinder in
the housing on air horn, and a fast idle con-
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