Jacob - the fast idle cam is a eccentric metal wheel with steps and a hole close to the center. A shoulder screw through the hole fastens the cam to the body of the carburetor, and the cam is permitted to rotate around the screw. The cam will be fastened to the choke butterfly valve. Moving the choke butterfly will cause the cam to rotate. The curb idle screw fits against the steps on the cam. When the choke butterfly is closed the cam will be rotated in such a way that the curb idle screw fits against the highest point of the cam, thus opening the throttle for a "fast idle". As the choke butterfly opens, the cam rotates to lower and lower steps contacting the screw. This causes the fast idle to slow to a normal idle.
Jon.
Last edited by carbking; 02/24/2011 8:33 PM.
