The replacement unit includes a magnet circuit support magnetic barrier member which includes the magnet unit of a Hall generator and is adapted to be fastened to the contact interrupter plate. The unit also includes a distributor rotor adapted for mounting on the contact interrupter cam of the distributor shaft. A plastic reinforcing member of higher mechanical strength is anchored in the distributor rotor. It has a keying projection and extends over the region surrounding said projection, thereby reinforcing the critical section of the distributor rotor. Preferably it is cap-shaped and has an opening for accommodating a retaining member which retains the distributor rotor in the desired position.

In an ignition distributor of a contactless controlled coil ignition system the stationary elements (16-21) of a Hall transducer are undetachably integrated in the distributor casing (10,30) or in a carrier plate (40). A plug connector casing (25,35) consisting of insulating material and providing with connector prongs (24) is spaced radially from the distributor casing (10,30) or from the carrier plate (40). The integration of the stationary elements of the Hall transducer and of the plug connector casing makes possible a construction of the ignition distributor that is compact and favorable for manufacturing technology.

Ignition control pulses as well as fuel injection control pulses can be obtained from a single signal generator structure by providing two generator units (28, 29) on the structure (1) which includes a rotating shield, vane or gate element (20) to generate by magnetic, for example Hall generator elements, or optical couplers, pulses (U28, U29). The vanes are so positioned, and the rotation thereof, at half engine speed, so arranged that the pulses (U28) generated by the first generator (28) extend over the pulse gaps or intervals of the pulses (U29) from the second pulse generator (29). At least one, and for example two vanes are foreshortened, so that the pulse generated by the first signal generator (28), upon passage of the foreshortened vane (23, 26) commences only when part of the pulse gaps of the second generator (29) has already elapsed. The pulse is applied to an OR-function gate which, then, will provide the fuel injection pulses; the trailing flanks of the pulses from the first signal generator are applied to control the ignition pulses, for example through a frequency divider (43). The number of vanes (22, 23 . . . 27) is twice the number of cylinders (in the example: three).

A lightweight distributor rotor driveshaft formed as a unitary structure. The unitary structure includes a socket member for engaging the rotationally driven element in the engine, at one end, and a mounting bearing surface configuration at the opposite end. The rotational bearing surface formed at the opposite end of the rotor driveshaft provides self-lubricating bearing surfaces which slide over fixed metallic surfaces within the distributor housing.

A hollow tubular structure of a distributor rotor driveshaft having a relatively high coefficient of thermal expansion is mated with an axially aligned metal driving member having a relatively low coefficient of thermal expansion. The tubular structure contains an internal socket configuration which conforms with and surrounds the external surface of the metal driving member. Rotational driving forces are communicated from the metal member to the tubular structure throughout a wide range of temperatures due to a compression spring that surrounds a portion of the tubular socket to restrict its expansion.