Abstract: A carburetor has a fast idle cam with at least two steps being progressively engagable by a throttle stop or abutment secured to the throttle shaft when the chock valve is closed; a lost motion linkage connecting the choke valve and fast idle cam permitting this action to provide for a cold engine start and the coldest fast idle cam setting with the throttle valve idle speed setting at the greatest opening, and a second cold start at a fast idle cam setting intermediate the coldest and a warm setting, to permit the throttle valve to be located in a less open idle speed setting but greater than the normal warm engine setting.

Abstract: Carburetor power valve control apparatus for an internal combustion engine. The control apparatus includes a vacuum motor and temperature sensitive power means. The power means opens and closes a vacuum bleed port in communication with the vacuum motor so that under cold operating conditions the power valve opens at a greater actual intake manifold vacuum than under warm operating temperatures. This results in earlier power valve opening at cold engine temperatures which improves drivability and allows balancing of all carburetor fuel systems to achieve improved fuel economy and reduced engine emissions.