Method and system for controlling ignition spark timing of an internal combustion engine of the multiple plugs type

In an ignition timing control system for an internal combustion engine of the type wherein first and second spark plugs are disposed in each combustion chamber, the improvement comprising:

• a breaker cam rotatably mounted in a casing;
• first and second signal generators disposed in the casing and cooperating with and operable by said braker cam, said first and second signal generators being electrically connected to the first and second spark plugs, respectively, and including means for generating the first and second ignition signals at different timings with a predetermined phase difference when the positions of the first and second signal generators relative to said breaker cam are changed to cause the first and second spark plugs to ignite with the predetermined phase difference;
• adjustment means for varying said phase difference by changing the positions of said first and second signal generators relative to said breaker cam;
• and
• an actuating device operatively connected to the adjustment means to move the adjustment means in response to a suction prevailing in an induction passsage of an engine carburetor of a throttle valve.