1. Different types of distribution

Since the design of the first engines, numerous distribution systems have been used. However, the quest for ever-higher specific power, greater reliability, and lower production costs and pollutant emissions (including oil consumption) have successively condemned most of these solutions.

This paragraph describes the main basic concepts, from which numerous variants have been devised. At present, only lights and valves are still used, for 2-stroke and 4-stroke engines respectively. The other solutions are presented for their historical interest.