This was a techtalk post but I have decided it is more appropriate as a blog entry:
Every day is a school day. This is for a 1987 car with Carbs, no ECU with Lucas 43D Dizzy.
I thought ignition advance was set with a timing light (or statically with a bulb) at x degrees before TDC and thereafter modified by vacuum advance (vacuum being taken from the inlet manifold - not ports).
Not quite. Massive absence of understanding by me.
I noticed what I thought were vacuum advance