The spark plug has an earth electrode (20) and a central electrode (40) which has a distance from the former so that an electrode gap arises. It has a combustion lower chamber (30), which contains the earth and central electrodes plus an annular wall (37) which surrounds the electrode gap and has several discharge holes which are located laterally beside the gap. The earth electrode has a width at its terminal end of between 2.5 and 3.5 millimeters. The discharge holes have an inner diameter of 3 to 4 millimeters. The combustion lower chamber has a cap which extends outwards from the annular wall and possesses a discharge hole at its one end.
