I am not so certain of your certainty, based on your description. Did you google "rotor phasing" as 67Dart273 suggested? There is a youtube video by MSD shining a timing light at the rotor tip to verify it aligned w/ the post when the spark occurred. I did this long ago, using a distributor cap w/ a hole to verify phasing, per Crane Cams instructions for their XR700 ignition (can find manual on-line).
