Abstract: An electronic fuel injection system operable as a bolt on retro fit replacement for a wide variety of carburetors is disclosed. The system includes a throttle body-injector assembly which, by means of an adapter may be bolted directly to stock intake manifolds using the carburetor mounting bolt holes in the manifold. The throttle body passages and injectors are designed to meet the fuel and air delivery requirements of large displacement engines and an electronic control unit which controls the solenoid actuated injectors in a duty cycle operation is provided with externally accessible adjustments by means of which the system may be adjusted to tune the rate of fuel injection to the fuel delivery requirements of engines of displacements much smaller than the largest displacement engine within the systems capability.

Abstract: A carburetor having an induction passage with a throttle valve therein has a fuel discharge port arrangement opening into the induction passage generally in the vicinity of an edge of the throttle valve so that as the throttle valve is more nearly opened the edge of the throttle valve, generally, traverses the discharge port arrangement as to effectively increase the functional flow of the discharge port arrangement and thereby effectively increase the rate of flow through the discharge port arrangement; a ledge-like surface situated generally in the induction passage and generally upstream of the discharge port arrangement results in an increase in turbulence of the medium flowing through the induction passage and a better atomization of the fluid flowing from the discharge port arrangement.