Kill switch: which wire from the coil?

[MissMoppet]

Please tell me which wire I should interrupt to add a kill switch?
Coil.jpg



Dave

[V Mad]

It would be helpful to know if you have points or leccy ignition.

None of those wires are standard colours so its impossible to be sure. If you only have one wire on one terminal of the coil then you can cut that one. If more than one you need to find the one that will kill the engine. Is that a ballast behind the coil?

[73stagman]

Wire a switch into the negative side of the coil. It doesn't matter if it is points or electronic ignition (because you are opening an earth circuit with your switch to stop the engine starting it cant do any damage to an electronic system. The coil switches on and off to make the engine spark and you are just interrupting the system to make it impossible for a spark to occur).
It will kill it dead and stop it restarting. (until you flick the switch and re instate the earth circuit)
You can also guarantee that only the coil will be turned on and off. With "modified" cars there could be other things that the feed to the coil is supplying. (You would hope not but you cant be sure but it doesn't look like it from your piccy. Looks just like a ballast resistor and bypass circuit)

[V Mad]

If its a Mk2 the coil NEG will also have another wire, for the tachometer. Its the other one you need to break.

[73stagman]

If its a Mk2 the coil NEG will also have another wire, for the tachometer. Its the other one you need to break.

Correct!!

[MissMoppet]

Electronic.

[MissMoppet]

Wire a switch into the negative side of the coil. It doesn't matter if it is points or electronic ignition (because you are opening an earth circuit with your switch to stop the engine starting it cant do any damage to an electronic system. The coil switches on and off to make the engine spark and you are just interrupting the system to make it impossible for a spark to occur).
It will kill it dead and stop it restarting. (until you flick the switch and re instate the earth circuit)
You can also guarantee that only the coil will be turned on and off. With "modified" cars there could be other things that the feed to the coil is supplying. (You would hope not but you cant be sure but it doesn't look like it from your piccy. Looks just like a ballast resistor and bypass circuit)

Many thanks for that. I think I'd better unbolt it, turn upside down and see if any of the wires are marked.