Amen, brother. In other words, the engine will run better rather than worse if you are adding initial advance to it, up to a point well past where we should be. So, if you truly are going to #'s higher on the clockwise, or right hand, side of the 0 then you must have waaaaay too much advance already in it. And the only way that can be is if you aren't looking at #1's spark or the harmonic balancer has slipped.

The balancer is a heavy ring of metal pushed onto the hub with a ring of rubber fused between. As they get old the rubber cracks and gets gooey from the environment in which it lives, and sometimes loses its grip on the metal. That lets the outer ring slip and the timing marks on it are worthless - as is the balancer.

Pull the plugs, preferably all of them so the engine is easy to turn, put a soda straw in the #1 cylinder, and turn the engine by using a 15/16" socket on the balancer's retainer bolt. Turn the engine clockwise and have someone watch the straw. You may have to keep a bit of pressure on it to ensure it stays in contact with the piston. But, as you turn the crank and the #1 piston comes up on Top Dead Center the straw will slow and finally quit moving. You need to stop turning the crank exactly when the straw quits moving as that is TDC. Now look at the timing marks to see if they show TDC. If so, the balancer is probably good. If not then you've found a problem. Maybe not the only problem, but at least it is a problem and the balancer must be replaced.