Thread: Magneto Kill Switch

Tweet

What you're looking for is a master electrical cutoff switch, not a magneto kill switch.
http://www.summitracing.com/parts/TAY-1032/
http://www.summitracing.com/parts/QCR-55-009/
http://www.summitracing.com/parts/PRF-50710/
Do not use a switch that has a removeable key. They're not legal.
The switch must kill the motor when turned off, as well as ALL electrical devices on the car. Once you have it installed, run the motor up to 3000 rpm and turn off the switch. If the motor still runs, the ignition switch of the car is being fed by alternator current. Disconnect the alternator to pass tech. Painless makes a solenoid that will cure the problem...
35 amp...
http://www.summitracing.com/parts/PRF-50103
250 amp...
http://www.summitracing.com/parts/PRF-50105
Or, if you're good at electrical things, install a diode in the line to the ignition switch to keep alternator current from back-feeding the system.
Now, before you decide not to make the system shut the motor off and just disconnect the alternator every time to pass tech and then plug it back in, let me lay out the worst possible scenario. I'm pretty good at doing this....
Your car has a mechanical fuel pump. You blow a tire in the lights and do a couple of rollovers, smashing the passenger side of the car so that the door doesn't open. The car ends up on its wheels up against the guard rail on the driver's side, so that you can't get either door open. You have been knocked unconscious. During the flipping, a motor mount broke and the engine heaved over enough to partially open a fuel line under the hood. The fuel is squirting all over the engine bay and has been ignited by a hot header tube. With the motor still running, the mechanical fuel pump is still pumping fuel into the fire. Remember those holes in the firewall that the tech guy told you to fix? Well, now they are a pathway for squirts of fuel into the driver's compartment. The fellow who works the E.T. shack has come running over to help and the first thing he does is turn off the master electrical shutoff switch. The motor continues to run because you didn't install the system correctly. Fuel still continues to pump into the driver's compartment.

If you think this worst case scenario is far-fetched, you'd better think again. It has happened before and it will happen again. Just about anything that you can possibly imagine has happened at the drag strip. Some fellows made it home that night and some didn't.