GarageYears.
That's why I proposed the distributor theory. Advance happens at a fixed speed. It's in the nose.
And I was wrong about the speeds. 2,200 is right in the band for centrifugal advance changes.
Currently I only have diesel engined cars here, so I can't take a gander, but my memory tells me that the stops for the weights are generally hammered pimples on the backplate.