Idle Speed-Up Control-With Air Conditioning; Accelerating Pump System; Low Speed Idle Mixture System; Idle Speed-Up System - Lincoln Continental 1964 Shop Manual

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IDLE SPEED-UP CONTROL-
WITH AIR CONDITIONING
On vehicles equipped with an air
conditioner, a mechanism is used to
increase the engine idle speed suffi-
ciently to overcome the additional
torque load incurred when the air
conditioner unit is on. This device
is an electrical solenoid switch which
operates an air valve in an external
bypass system of the carburetor, to
increase air flow below the throttle
plates (Fig. 10).
The idle speed-up valve oper-
ates only when the air conditioner
unit clutch is engaged. The solenoid
is not affected by throttle position or
manifold vacuum; it is controlled
solely by the clutch. It is not nec-
essary to operate the air condition-
ing system when adjusting the
curb idle speed.
ACCELERATING PUMP
SYSTEM
The accelerating pump system, lo-
cated in the primary side, provides
a measured amount of fuel neces-
sary for smooth engine operation on
acceleration at low speeds (Fig. 11).
When the throttle is closed, the
pump plunger moves upward in its
cylinder and fuel is drawn into the
pump cylinder through the intake
check valve. The discharge check
needle valve is seated at this time
to prevent air from being drawn into
the cylinder. When the throttle is
opened, the pump plunger moves
downward, forcing the fuel out
through the discharge passage. The
fuel is forced through a diagonal
passage to the discharge needle. The
force of the fuel unseats the needle
and fuel is free to flow through a
restriction into the discharge nozzles.
When the plunger moves downward,
the intake check valve is closed, pre-
venting fuel from being forced back
into the bowl.
At high speed, accelerating pump
discharge is not necessary for smooth
acceleration. When the throttle plates
are opened a predetermined amount,
the accelerating plunger bottoms in
the cylinder, eliminating discharge.
During high speed operation, a
vacuum exists at the discharge noz-
zles. To prevent fuel from being
drawn through the system, the dis-
charge nozzles are vented by a cavity
between the pump restrictions and
discharge nozzles. This allows air
instead of fuel to be drawn through
the discharge nozzles.
PART 1 0-2- CARTER CARBURETOR 10-15:
IDLE MIXTURE ADJUSTING NEEDLE
81961-A
FIG.
9-Low Speed Idle Mixture System
SPEED-UP AIR PASSAGE
¢AIR
81962-A
FIG.
10-ldle Speed-Up System