Kill Switch Wiring

I think it breaks the negative contact.

I assume (someone please help me and Wombat here) that you can put a kill switch in the positive feed to the coil or the ground from the coil and it will prevent the engine from running.  Basic Automotive for $100 please Alex.

However, answer Wombat's question first.  I'll start a new thread with a similar but different question.  See: "Coil Lock Out through steering column ignition switch".

thanks

I kinda think that when you close the kill switch it shorts the negative side of the coil (terminal 1) to chassis ground. But I'm not sure. And if I'm right, what happens if you keep it shorted and try cranking for a long time? Does it damage the coil? 

It doesn't short it,  it just breaks the circuit.   Same as a light switch in your home. 

No, I'm thinkin it actually shorts the negative side of the coil to ground.

Grounding the negative (distributor/tach) side of the circuit will certainly prevent the car from starting and is reasonably safe to do with a distributor running points.  It would also prevent someone from hot wiring your car, especially from a tail light circuit (Merklin's favorite way of swiping VWs back in the day) and no one ever thinks to hot wire the disti pulse ground, too (and that takes time).

If that switch is closed and it is grounding the coil negative side AND the ignition is turned on, the coil will begin to get warm and then hot (takes a few minutes) - how hot depends on the coil.  If you have points in the distributor (not an electronic ignition) then nothing happens to the points.  If you have an electronic module in the disti, I'm not sure how the different ones handle that, but it should probably be OK, too.

In rereading his original post he did say that one side goes to ground, so you're probably right Gordon.