Abstract: An internal system for use in an internal combustion engine which includes a carburetor, a throttle valve and a check valve. A supplemental chamber is connected to an intake passage adapted to introduce therethrough air-fuel mixture from the throttle valve to a combustion chamber. The supplemental chamber is in communication with the intake passage at a position between the throttle valve and the check valve. The supplemental chamber is provided with an opening directed tangentially with respect to an inner cylindrical periphery of the intake passage. In another embodiment of the invention, a control passage is formed in communication between the supplemental chamber and the intake passage. A downstream end of the control passage is opened at a position adjacent to an initially opening position of the check valve.

Abstract: An ignition timing control system for internal combustion engines during warm-up utilizes opposed chambers separated by a flexible diaphragm to control movement of a rod to advance or retard the ignition timing. Temperature responsive electric switches energize electromagnetic valves to control vacuum pressures in said chambers, so that as a cold engine warms up, the ignition timing changes from advance to retard in a series of steps.