What effect does increasing or decreasing vacuum from the VCV have on shifting on an 84 SD (722.303)?

I need to (and will) replace my pressure gauge and have forgotten what pressure the modulator is set at. Trans still shifts a little early and a little hard in both 1-2 and 2-3 shifts.

VCV max is 10" and drops to 0 at ~10mm of travel per FSM. Bowden is adjusted out.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

It controls the harshness or softness of the shifts at varying accelerator points.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13