[K7Sparky]

As I remember it sort of tunes the vibrator like a cap across the points in the distributor did the ignition coil.  Too much C one side of the points burn faster loo little the other side burns faster.

Also suppresses the arc noise from the vibrator.  The inductive voltage spikes are HIGH thus the 2KV rating.

Haven't had a reason to try it but a MOV across the points - parallel with the cap - might help with point burn.  Alternatively might stop the vibrator action dead.  Had mixed results with MOV across large DC contactor coils.  Sometimes helps  Sometimes the MOV holding down the voltage during inductive decay causing a longer decay / drop out time causes timing problems.  The stored energy has to dissipate so lower decay voltage causes longer delay / drop out time.

I found a great vibrator replacement book that had lots of specifications for vibrators.  Among the data was the recommended capacitance.  If you care I will try to find the link again.  Referenced in a post awhile back.

Another good reference from Tubebooks Vibrator Power Supply Design,