The head for a filler pipe of a vehicle tank provided with an obturating assembly includes: a body having a passage aperture; and an obturator pivoting relative to the body between an obturating position and a freeing position. The obturator is elastically biased towards the obturating position by a spring. The obturator includes a seal disposed in the obturating position between the obturator and a sealing seat that the body comprises. The head includes a hinge to pivotally mount the obturator on the body. The relative positioning between the seat and the pivotal axis defined by the hinge is fixed. The seat is flat and the obturator includes a plug provided with the seal and a flap mounted on the body by the hinge and biased by the spring with the plug which is mounted on the flap by virtue of a ball joint.