Manifold Vacuum Advance what am I not getting?

Bewy said
^^^^ No
1" of Hg = 3.4 kpa, so 100 Kpa is about 30" of hg.

Yes as a direct conversion BUT I wasn’t clear. The Y-axis is MAP or Manifold Absolute Pressure.

MAP = Barometric Pressure - Vacuum

Then you have to convert to Kpa if your using In-Hg for Baro and Vacuum.