An engine has an engine body having an outer surface that defines an outer area next thereto. An air intake system has an intake valve movable between a closed position and an open position. An intake camshaft that actuates the intake valve extends through the engine body and toward the outer area beyond the outer surface. A drive mechanism drives the camshaft. A portion of the drive mechanism is disposed in the outer area. A hydraulically operated change mechanism changes an angular position of the camshaft relative to a crankshaft. A control valve unit controls the change mechanism. The control valve unit at least in part is disposed within the outer area.