[Y-Blockhead]

Originally Posted by Tom Endy

The rubbing block on the points wear down as you drive the car. This causes the points to close up. The ignition timing is set after the point gap is set. Usually set at a nominal .020. As the points close up it changes the timing. They tend to close up faster on a new set of points. On a new set they can close up considerably in just 100 miles. After that the wear is not as severe. You will notice them closing up while driving as you will have to keep retarding the spark by pushing the spark handle up.
Tom Endy

I don't think that is correct. When the points block wears, the points close, retarding the timing. You would have to advance the lever (pull down) to compensate.