[lrf]

dkrahn, the cam spins on the upper shaft, that's how you adjust the rotor and timing. Once the rotor is positioned correctly, remove the rotor and tighten down the cam screw, there is a thin lock washer that goes under the cam screw needed to keep the screw tight,
don't forget to replace the rotor (something we've all done). Good luck and Drive and Enjoy your "A". LRF