Extended throttle bore multi-stage carburetor

Claim 1

In combination, a dual stage carburetor having primary stage and secondary stage induction passages each having an air inlet at its upper end and a discharge opening at the other lower end, an engine intake manifold extending essentially at right angles to the axis of the passages and having an engine exhaust gas heated floor portion directly beneath and aligned with the lower discharge ends of the primary and secondary induction passages for the splash of fuel against the floor portion to warm the fuel and aid in the vaporization thereof, the primary induction passage having a fuel metering venturi receiving fuel therein for induction of fuel into the manifold, the primary passage discharge end extending into the intake manifold into close proximity to the floor portion but spaced therefrom so as to vaporize the fuel mixture discharged thereagainst while permitting a controlled flow of mixture out of the space between the primary passage and floor portion towards the engine cylinders, the discharge end of the secondary induction passage being concentric with and surrounding a lower portion of the primary passage and terminating adjacent the inlet to the intake manifold so as to discharge air into the manifold in a manner bypassing the flow restriction caused by the extension of the primary passage into close proximity to the floor portion, and control means controlling flow of air through the secondary passage.