The dwell angle is the number of degrees per cylinder that the points are closed/coil charging in one rotation of the distributor. Electronic ignitions work the same way.

Maybe some but by no means all..... Many EIs have single trigger point (Pertronix uses a magnetic signal while my old Piranha uses an IR beam/chopper). The timing is set using pretty much the same system as a points setup in the the coil (and plugs) are fired by the points opening or magnetic/IR pickup triggering.

With points, they close and the coil is charged until the points next open... With EIs, the little black box switches the coil charge on based on some form of logic in the box. Presumably it's time related because there's no sensor available to measure any rotation of the dizzy....

EIs work better because A. they don't wear like points; B. they don't suffer from spark scatter due to a worn dizzy shaft (so timing is more accurate and stable) and C. (one assumes because I really don't know) they can vary the voltage/current fed to the coil to compensate for the reduced coil charging time as revs rise. (I've not found an explanation for what/how the circuit(s) inside the little black box on my Piranha do)... but they're there so they must do something.....

??????

Cheers, Ian

I am not convinced that electronic triggers do not suffer due to a worn shaft or bush as that still has the same effect on the trigger ring. Obviously a worn cam or points heel would not affect it though.