When is too much timing advance too much?
 

My car runs 35+ advance under revs. Looks like the centrifugal advance spring inside the distributor is shot (still advances with vacuum disconnected)

The car moves pretty well, I'm wondering will I lose power when the timing is adjusted back to the 25 degrees spec, or should I see more power because 35+ is too far ahead?

I do know this: if the timing goes way too advanced, you will experience detonation = damaged engine, possible holes in pistons.