ring in distributor

[metalcutter]

94 4.3L TBI
I was looking at the distributor and notice that this ring moves.

EDIT - should have said the outer ring moves 10 to 20 degrees relative to the distributor shaft !!!!

- is it supposed to move?
- should it move freely?
- what is the function of this ring?
TIA

[LiftedAWDAstro]

Is that the advance mechanism?

[brokenwrench]

Is that the advance mechanism?

when that rotates past the pickup coil it induces an electrical field which is the signal to the ingition control module to collapse the field in the coil. advance is controlled electronically unless you have a 1985 -1986.

[metalcutter]

the electronic advance by the computer makes sense.
the outer ring is easily moved relative to the distributor shaft, using just my fingers.
if it triggers the timing pulse to the computer then I would think the ring shouldn't move otherwise there would be erratic timing.