Abstract: A dual duct porting system comprises a pair of juxtaposed bent, side entry supply ducts (14, 15) merging into a single supply passage (16) encircling a valve stem (13). Each supply duct (14, 15) has eddy creating means (20) provided at a radially inner region of the duct bend and an outwardly bulging portion (21) at a radially outer region of the duct bend to provide a flow in the merged passage (16) which is more evenly spread around the valve head to be shed therefrom as evenly distributed toroidal vortices.

Abstract: Liquid fuel from a controlled supply is delivered to a delivery tube under a pressure which is too low to deliver a charge of fuel under static conditions. During an induction stroke however, air entering a cylinder of an engine is drawn through a venturi-type constriction and thereby draws air from a duct by-passing the engine throttle. This air is drawn through a convergent passage to pass the delivery end of the tube at supersonic velocity to draw therefrom a charge of fuel. The tubes for each inlet passage are in permanent communication with the same metered supply so each cylinder draws its appropriate charge in turn.

Abstract: Fuel for a working cylinder chamber (8) of an internal combustion engine is drawn through an atomizing nozzle (39) from an accumulator (30). Fuel is supplied by a low pressure source (12) through a variable constriction (16) linked to the throttle (4) and through a solenoid valve which is pulsed at a frequency proportional to engine speed.