Staged carburetor

A staged carburetor for an internal combustion engine comprising:

• a carburetor body in which at least one pair of induction passages is formed for air to be drawn into said engine, said pair of induction passages including an inner induction passage having a venturi therewithin and an outer induction passage encircling said inner induction passage;
• a throttle valve positioned at the outlet of said pair of induction passages and movable between a closed and an open position to control the flow of air through said induction passages;
• at least one fuel circuit through which fuel is delivered from a source thereof to said inner induction passage, said fuel circuit having an outlet at said venturi;
• a metering rod extending transversely of said induction passages and having a variable diameter end portion projecting into said fuel circuit outlet, said metering rod being movable relative to said outlet to vary the quantity of fuel delivered;
• an air valve positioned in said outer induction passage and normally closing said passage whereby air is initially drawn into said engine only through said inner induction passage, an increased demand for air by said engine resulting in an opening force being exerted on said air valve to open it so air is drawn into said engine through both induction passages, said air valve being a split valve first and second sections each respectively closing a portion of said outer induction passage, each section of said air valve being attached to a rotatable shaft;
• means linking said air valve to said metering rod to move said metering rod relative to said fuel circuit outlet as said air valve opens to change the quantity of fuel drawn into said inner induction passage, said linking means comprising a first fixed lever rigidly mounted on one end of one of the air valve shafts, a second fixed lever rigidly mounted on the corresponding end of the other air valve shaft and a connecting rod connecting said first and second fixed levers to form a solid connection therebetween whereby movement of one of said air valve sections produces a simultaneous corresponding movement of the other air valve section, a rotatable counter shaft and a lever carried by said counter shaft, said lever contacting said metering rod to exert a force thereon to withdraw the variable diameter end portion of said metering rod out of said fuel circuit outlet when said counter shaft is rotated in one direction and to insert the variable diameter end portion of said metering rod into said fuel circuit outlet when said counter shaft is rotated in the opposite direction, a third fixed lever rigidly mounted on the end of said counter shaft corresponding to the ends of said air valve shafts on which said first and second fixed levers are mounted and a second connecting rod connecting one of said first and second fixed levers to said third fixed lever whereby the opening movement of said air valve produces rotation of said counter shaft in the direction to withdraw the variable diameter end portion of said metering rod from said fuel circuit outlet and the closing movement of said air valve produces rotation of said counter shaft in the direction to insert the variable diameter end portion of said metering rod into said fuel circuit outlet, means for delaying the movement of said metering rod relative to said fuel circuit outlet until said air valve has partially opened, the quantity of fuel delivered to said inner induction passage at any one time mixing with the air flowing through the passage at that time to produce an air-fuel mixture combusted in said engine, the air-fuel ratio of the mixture being that necessary for proper operation of the engine.