Method of and apparatus for generating cylinder discriminating signal in distributor for internal combustion engine

A method of generating a cylinder discriminating signal in a distributor for an internal combustion engine having a rotary shaft rotated synchronously with said internal combustion engine, a centrifugal spark advance member rotated through a centrifugal spark advance mechanism so that said member revolves relative to said rotary shaft, an ignition timing reluctor provided on said centrifugal spark advance member, a vacuum spark advance plate, and ignition timing signal generating means for generating an ignition timing signal by detecting approach and passage of said ignition timing reluctor with respect to sensing means provided on said vacuum spark advance plate, said method comprising generating a cylinder discriminating signal by a combination of a cylinder discriminating reluctor installed on said centrifugal spark advance member, said cylinder discriminating reluctor having a width in the direction of rotation which corresponds to an angle smaller than the entire range of spark advance of the ignition timing signal, and a cylinder discriminating sensor attached to said vacuum spark advance plate to detect approach and passage of said cylinder discriminating reluctor, so that the cylinder discriminating signal is advanced by both centrifugal spark advance and vacuum spark advance so as to overlap the ignition timing signal over the entire range of spark advance of the ignition timing signal.