base timing keeps advancing by itself...

If the inter shaft was spinning in the gear, you would get no oil pressure.....

I never use Pertronix products because of the BS. They claim the Ignitor 1 doubles the secondary voltage. It doesn't & voltage doesn't change, assuming the same coil is used.
Not sure if that version uses a slotted wheel/window for triggering, but if it does I'll bet it is moving & changing the timing.