Carburetor and metering device therefor

A liquid fuel metering device for use between a liquid fuel reservoir and a main body of a carburetor to meter the fuel delivered to the main body from the fuel reservoir, the metering device comprising:

• a block having a first face adapted for engagement with the fuel reservoir and a second face adapted for engagement with the main body;
• a primary fuel supply path including a primary intake port in the first face of the block for intake of liquid fuel from the fuel reservoir, a primary exit port in the second face of the block through which fuel may pass into the main body, and a primary passage extending from the primary intake port to the primary exit port for transport of fuel from the primary intake port to the primary exit port;
• a main air bleed associated with the block and constructed for receiving air, the main air bleed including means for delivery of air from the main air bleed to the primary passage for mixing air with fuel in the primary passage, said air delivery means comprising at least one conduit which extends between the main air bleed and the primary passage, said one conduit opening into the primary passage at a first location which is the location nearest to the primary intake port where air is introduced to the primary passage;
• adjustable fuel flow control means for adjusting the effective cross sectional area of the primary passage at a second location between the first location where air is introduced into the primary passage and the primary intake thereby to selectively alter the flow of fuel through the primary passage, the block and said adjustable fuel flow control means being constructed and arranged for adjusting the flow of fuel through the metering device from a location exterior to the block when the first and second faces of the block are engaged with the fuel reservoir and the main body, respectively, said adjustable fuel flow control means comprising a rod received in the block and having a metering portion disposed in the primary passage at said second location, the rod being pivotable about its longitudinal axis between multiple discrete metering positions for adjusting the cross sectional area of the primary passage at said second location thereby to change the flow of fuel through the primary passage, each metering position corresponding to a predetermined jet number;
• and
• a detent mechanism for selectively holding the rod from pivoting about is longitudinal axis in a selected one of the multiple metering positions thereby to securely fix the rod in a selected one of the multiple metering positions, the detent mechanism comprising a detent movable with respect to the rod and block in directions non-parallel to the longitudinal axis of the rod for fixing and releasing the rod in the selected metering position.