I've read dozens of times how advancing or retarding the cam affects an engine, but the only real way to find out is to actually run it in all three positions and see how it does. Without actually knowing how your cam is actually ground in respect to centerline (and the only way to know that is to degree it yourself) no one can for certain tell you if you need to advance or retard it. So all that considered, I just run em straight up going by the timing marks. Never had a regret from doing it this way.