RE: gas fuel with glo plug no ignition
I have restarted an engine while diving from high up.
That said you would, heat one glow plug.
At higher RPM the 2nd plug would start to glow.
So the 2nd plug would need to be a colder plug, I'm guessing.
That would give you advance with a curve.
Both plugs the same would also give you advance with out a curve