Fiat 124 Spider - Page 34

FIAT 124 Spider
Engine Maintenance + Modification
34
Should the accelerator be depressed when the choke is included, the screw (61) would
disengage the cam (60) which drawn by spring (63) would reduce the opening of primary
throttle (23).
The engine cooling-water warms up, and, circulating in the cover (70) heats the bimetallic
coil (58) which will make the lever (67) turn and through the above mentioned linkage
system, will cause the progressive opening of choke plate (59). During rotation of
primary throttle (23), the cam lever (60) will also rotate thus excluding progressively the
choke.
Once running temperature is reached, the choke plate (59) will be in fully open position:
the screw (61) is now no longer in contact with the cam (60) thus allowing primary
throttle (23) to close up till to normal idling position.
Figure 31: ADF Anti-Pollution Device
ADF type carburetors, provided with vacuum devices to reduce air pollution, are fitted on
cars equipped with electric switches that set off a special electro valve located between
intake manifold and fuel inlet pipe (74).
The vacuum, through pipe (74), acts on diaphragm (73) which, by means of rod (72),
lever (71) and lever (53), opens primary throttle (23) to fast idle position: adjustment of
throttle (23) opening is carried out through adjusting screw (75).
Under such opening conditions, during motoring over, exhaust emission levels are rather
low; within the air pollution tolerances. When vacuum is intercepted by the electro valve,
the air sucked through duct (76), nullifies vacuum acting on diaphragm (73) and allows
throttle (23) to return to normal idling position.