Oh yes, the shirt button answer to plug oiling! Thats how all those "Ignition supercharges" you could buy worked, but they cost a bit more !No the HT circuit doesn't need to be broken, its the switching off (breaking) of the primary winding that induces a high voltage in the secondary. If that's any help.
Keep in mind some coils have an air gap in the secondary to force the voltage to jump the gap, this ensures a high voltage spark at the plugs, especially useful when on the TVO.
Some had top coat buttons on the plug leads with the copper through adjacent holes again forcing the spark to jump an air gap, before it reaches the plugs.
Why don't they just use SW and CB?
The contact breaker is always on the earth side, so just connect the coil the same as the battery.So when my new coil arrives and it's marked positive and negative, how do I know which terminal is the common terminal to the LV and HV coil?
Does the supplier of the coil anticipate a negative earthed vehicle nowadays, in which case the distributor should be connected to the -ve terminal, or does he anticipate a positively earthed vehicle in which case the distributor should be connected to the +ve terminal.
I know it doesn't make a lot of difference but is there a convention or a way of finding out?
Why don't they just use SW and CB?
The contact breaker is always on the earth side, so just connect the coil the same as the battery.