In order to make possible the lower level of electrostatic disturbance that accompanies the use of a wider than usual gap in an ignition distributor without undesirable increase of the ignition pulse voltage, the distributor electrode and/or the fixed ignition circuit electrodes of the distributor are made at least in part of a material that requires less energy for pulling out an electron and has a higher secondary electron emission capability than the usual brass plate used for the contact plate at the axis of revolution of the distributor rotor, to which a carbon brush is usually provided for making contact. Alloy additions of calcium oxide or barium oxide or silicon to brass have a suitable effect and an alloy containing silicon and preferably also aluminum and calcium is preferred. The gap width is between 3 and 5 mm, preferably about 4 mm for normal motor vehicle engine application.