Figure 4-36.Exhaust-manifold heat-tube choke.
the carburetor with a fast idle cam (fig. 4-37) that is
operated by linkage from the choke.
When the choke closes, the fast idle cam swings
around in front of the fast idle screw. As a result, the fast
idle cam and fast idle screw prevent the throttle plate
from closing. Engine idle speed is increased to smooth
cold engine operation and prevents stalling. As soon as
the engine warms, the choke opens and the fast idle cam
is deactivated. When the throttle is opened, the choke
linkage swings away from the fast idle screw and the
engine returns to curb idle (normal, hot idle speed).
If for some reason the engine should flood when it is
cold, a device is needed to open the choke, so air may be
admitted to correct the condition. This is accomplished
Figure 4-37.Fast idle cam operation.