Variable cylinder operation of internal combustion engine

Abstract

An insert plate is provided for mounting between the base mounting flange of a carburetor including a pair of air and fuel passages extending therethrough and an intake mounting boss having a corresponding pair of air and fuel passages formed therein with which the carburetor passages may be registered. The insert plate includes a pair of openings formed therethrough for registry with the carburetor and intake manifold air and fuel passages and defines an inlet extension of the manifold. A valve member is shiftably supported from the plate for movement between one of three positions, including a first position closing only one of the openings with the second opening unobstructed to the flow of fluid therethrough, a second position closing only the other of said openings and with said one opening unobstructed to the flow of fluid therethrough and a third out-of-the-way position with each of said openings unobstructed to the flow of fluid therethrough. Shift structure is operatively associated with the valve member, the latter being yieldingly biased to the third position thereof, and the shift structure is operative to alternately shift the valve member to the first and second positions thereof responsive to sequential operation of an associated engine. Further, the shift structure is also operative to automatically allow the valve member to shift to the third position thereof responsive to heavy load operating conditions of the associated engine.