Ok, a little credit!
Most people don’t do it that way.
I’ve set it like that a few times with the bumper tied to a power pole when the emergency brake cable was broke.
I’ve used a vac advance limiter like in this link to control total vac advance.
http://www.crankshaftcoalition.com/w...EI_distributor
Your motor likes lots of initial. Likely your vac pot needs a few tweaks.