A combustion engine for a vehicle includes a device for changing the timing of suction/relief valves with respect to the drive shaft. The device includes a first disc idly mounted to the camshaft and has a first side defining first slot tracks. A second disc is integral with the camshaft and includes second slot tracks facing the first side of the first disc. Drive elements transmit motion between the first disc and the second disc and each is accommodated between corresponding two of the partially facing tracks. As centrifugal forces caused by the rotation speed of the camshaft changes, each drive elements moves between a first reference position and a second reference position which are close to and far from the rotation axis of the camshaft, respectively. A phase changer device exerts a force which tends to oppose movement of said drive elements towards the second reference position.