Do not leave the key on with their coil. I've had 3 blow when we forgot to turn the ignition off while testing other things without the motor running. If you need to do so, disconnect the + side of the coil.
This is good to know , a friend of mine called me a couple weeks ago with a problem with his car I swapped a Pertronixs into after he was at a car show and left his ignition on for an hours or so. I'll call him and tell him to swap the coil and see if that fixes it .
