Air valve carburetor with engine starting fuel enrichment means

Claim 1

An air valve type carburetor having an air/fuel induction passage open at one end to air at essentially atmospheric pressure and adapted to be connected to an engine intake manifold at the opposite end to be subject to the changing vacuum therein, a throttle valve slide variably movable across the passage between positions fully opening and closing the passage, a fuel jet opposite the slide subject to the flow of air therepast to induct fuel into the passage, a needle valve movably carried by the slide projecting into the fuel jet and means movable at times by engine vacuum to vary the fuel jet size as a function of changes in vacuum, the slide having an aperture therethrough communicating with the fuel jet and providing the sole supply of air to the engine during closed throttle valve engine shut off, idle speed and deceleration operation, and engine starting fuel enrichment means operative when the engine is cranked to supply a starting fuel supply mixture to the engine, and rendered inoperative in response to the attainment of a predetermined engine vacuum to discontinue the fuel supply, a control valve in the line biased to an open position, the line having an outlet in the induction passage downstream of the slide, vacuum at a predetermined level corresponding to normal engine running operation acting on the control valve to block the line and terminate fuel flow, and other means operative at lower levels of vacuum forces indicative of engine acceleration modes to block the line and override the opening of the line by opening of the control valve.