I thought most engines like a total of 30-36 degrees "total" advance at Wide Open Throttle (WOT).

Why is the stock A12 distributor only 17.5 degrees total (5

Good question.
I've been thinking about this lately. I Hope to soon fit my New old stock electronis dizzy. I was thinking About limiting how much mech advance it can get, But I'm very reluctant to butcher a brand new dizzy. How much vac advance do they have? I was contemplating having the diaphram converted to a boost retard unit. Once the nitrous is on, any rattles will mean instant death for the pistons.

The Factory Service Manual lists the curves and specs.

Anyone have an Aussie FSM?


In USA, all A-series through 1982 are very similar:
- 11.5

the y axis on those graphs says distributor angle, which as dizzy turns at half engine speed would be doubled for crank angle- is that a possibility?
My manual (not a factory one) says 5-10btdc depending on model, so if you doubled the above you would get anything from 28-35 total which would seem reasonable?

That seems to make sense...