Intake manifold for internal combustion engines

Claim 1

In an intake manifold for an internal combustion engine, said engine having a plurality of main combustion chambers, a plurality of auxiliary combustion chambers communicating with respective ones of said main combustion chambers, and a carburetor unit, said intake manifold having: an interior thereof formed with a plurality of main intake passages connected to respective ones of said main combustion chambers, a plurality of auxiliary intake passages connected to respective ones of said auxiliary combustion chambers, a main distributing chamber from which diverge said main intake passages, and an auxiliary distributing chamber from which diverge said auxiliary intake passage in two substantially horizontally opposite directions, said auxiliary distributing chamber being disposed to overlap with said main distributing chamber at a location downward thereof in a vertical direction, said main distributing chamber and said auxiliary distributing chamber being adapted for connection to said carburetor unit at a location downstream thereof, said intake manifold having a partition wall extending through said main distributing chamber along the entire length thereof in a direction of flow of a mixture therein and dividing said main distributing chamber into a primary distributing chamber and a secondary distributing chamber, the improvement wherein said partition wall has a boss, and an intake guide passage formed through said boss, said intake guide passage opening at one end thereof in an outer surface of said intake manifold, said outer surface forming a carburetor-mounting surface, and opening at another end thereof in said auxiliary distributing chamber, said other end of said intake guide passage being directed toward a horizontally substantially central location of said auxiliary distributing chamber.