That article is very informative but has left me still confused. He talks of vacuum pots taking their signals from manifold (below throttle plates) vacuum and wanting a pot that is all in when manifold vacuum is high (idle, partial throttle cruising, etc.) All of this is in line with what I have always understood and how I have always set up my engines. Where does the use of ported vacuum (above throttle plates) come in then? Since it is desirable to have max vacuum advance @ idle and part throttle cruising, it appears that ported vacuum can perform properly in neither case. Rather, it would pull maximum advance @ WOT, higher speed, and accelerating condition which is exactly when you DON'T want extra advance over initial and centrifugal advance.