[chiphead]

I thought that no vacuum would make the tranny shift very late? With no vacuum, the tranny thinks the engine is at WOT and not making much vacuum. Then it should shift late, when governor pressure (road speed) overcomes vacuum modulator pressure (engine load). With high vacuum, the tranny thinks the engine is lightly loaded and shifts early.

That's why turning the adj modulator clockwise to increase spring pressure on the diaphragm makes it shift a little later, more vacuum is then required to move the diaphragm. If that's not enough adjustment, you'll have to play with the governor springs to adjust shift MPH and shift spacing.

At least that's how it works on my TH350.