[David Ray]

"Please explain how a vacuum operated load compensator would ADD timing at acceleration? "

Welllllll, as we all know, full manifold vacuum REDUCES upon engine acceleration, because engine vacuum reduces as throttle position is increased, during engine acceleration. So, there would be no additional timing, no second acceleration curve as this occurs.

PORTED vacuum is moot at low to no load, and high engine vacuum levels, such as no to light load cruise, and when the engine is accelerated, vacuum is created at the ported port, bringing into operation, the 'load compensator', forcing it to work completely opposite of how it should, adding vacuum advance degrees upon engine acceleration, CREATING A SECOND ACCELERATION ADVANCE CURVE ADDED TO THE MECHANICAL CURVE, MAKING TWO DISTINCT ACCELERATION CURVES.

That's how.