A cam phaser mechanism includes an inner ring (rotor), and outer ring (stator), and a face plate. The inner ring that is wider than outer ring. The face plate is contoured such that it is thinner in a region in contact with the inner ring and thicker in a region in contact with the outer ring, thus compensating for the different widths of the inner ring and outer ring. The stator is fastened to the face plate by a plurality of bolts which are threaded into the face plate. The greater width of the face plate in this region provides sufficient thread engagement without increasing the overall width of the cam phaser mechanism.