Manifold Vacuum Advance what am I not getting?

Newbomb Turk said

Not always. Where the throttle blades are relative to the ported vacuum port changes when you get ported vacuum.

The curves don’t necessarily have to be the same.

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I’ve seen side-by-side comparisons of ported versus manifold gauges while driving. They don’t always do the same thing everywhere. I was surprised that there are differences. I think they’re minor though, but they are different.. But for the sake of this conversation, I’m assuming that they’re very close and that the only differences tuning.