Low octane fuel and hot engine?
If ignition is off there is no power to make a spark (excepting the rad fan possibility), timing adjustments would be moot, no?
I put 5 gallons 87 into the car once in a pinch, it dieseled so badly when I got home I had to put it in gear and release the clutch to stall it.
5 gallons of 110 race gas fixed it. Never ran 87 again.