Thread: Magneto Kill Switch

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For you guys running mag ignition, what brand kill switch are you using? I have purchased the Flaming River dual 12V/Mag kill switch, but have had problems with it. Had to return it twice due to the Mag grounding function not working.

I can't find any other manufacturer's out there. Can F/R be the only source?

http://www.jcwhitney.com/magneto-kil.../p2029043.jcwx
http://www.speedwaymotors.com/Magnet...itch,3946.html

I just use whatever switch that is handy.

Tech,
Thanks for the tips. The type of switch I mean is the one required by regulation to be mounted in clear view at the rear of a drag car. You know what I mean, so a Tech guy, or Rescue guy can kill fuel, ignition, 12V... everything. 12V on/off switches abound, but Flaming River is the only one I can find that has the dual 12V/Mag kill function. And, they are pricey, at over $110. You'd think at that price, they'd work correctly! Rad

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.

Thanks again, Tech.

If I install a batt kill switch, as I have done many times, all 12V will be shut down. True. However, a magneto does not have anything to do with the 12V system. I could be up against the guard rail, and the rescue guys push in the plunger, and the mag will keep providing spark until the float bowls run out. If you tech a car, and ask them to start it up, and push/turn the kill switch and it keeps running, you will not pass them. I need a way to kill the 12V and ground the mag with one safety switch. Flaming River is the only dual 12V/Mag grounding switch I have been able to find. And the results have been less than good. Perhaps I need to go with a relay that triggers on removal of 12 volt power and thus grounds the mag.

Originally Posted by drofdar

Perhaps I need to go with a relay that triggers on removal of 12 volt power and thus grounds the mag.

Bingo!!!!!
Sorry, I went off on a tangent about battery ignition because that's what I see on 99.9% of cars.

A relay that opens when 12 volts are applied and closes when power is shut off is what you need put it in line beetween your shut off switch and ground. have the 12 volts acivated by the main shut off sswitch inthe back that should do the job

Heres pics of the battery disconeect and magneto kill switch in my car. The switches are 75amp push-pull switches. When the rod is pulled out the battery switch makes contact and closes a solenoid up on the passenger floor, the solenoid is the battery disconnecting means; the magneto switch opens and removes the fround from the magneto. With a single push of the kill switch rod the magneto is killed and the battery power is removed.
The other pic is the switches at the driver, both switches lift up to turn 'on' and they do the same thing as the rear switch, both sets have to be 'made' before the car has power or the engine can fire.

Thanks for all the help. I think a relay is the way to go. I'm really surprised that Flaming River sells such an expensive solution to a very important component that doesn't always work.

I wouldn't go with a relay, if it is on the N/O side then whenever the power is 'off' the engine is able to fire up and run; if it is on the N/C side then the relay (a $5.00 part) is the lifeline of the car. If it were up to me i would want a competitor to use a relay.
I don't know how much power you are making nor how violent, but if the contacts in that relay 'break' and then 'make' when launch or burnout you will have one hell'uva explosion thru the exhaust - just something to consider in your calculations.

I just reread the post and it didn't come out right, when i wish that a competitor used the relay i meant that at some point the relay will fail and he won't be able to come to teh line. I would not want to see anybody have an engine explosion and that possibility occured to me as i was writing the above post.

Good points ojh. There are certainly decisions to be made regarding mechanical vs electrical reliability. Things do break. That is why I never rely on the neutral safety switch when starting up and always make sure the handle is in "Park". Last year at Sacramento Raceway, a dragster started up and started running in reverse breaking a young boys leg in the lanes! Fortunate it was not worse. That was a mechanical problem. I do use relays, such as the one that powers my Holley Black fuel pump. It goes out - no race today! Regarding the mag relay, it must be on the non powered side, as the power is what holds it open (mag not grounded). As for starting, when the safety switch is activated, no 12V power to the starter means the engine will not start, even if the mag is not grounded anymore. Although, I guess it could be "push" started.
I am mostly interested in the darn thing working in the event of an accident. And, Flaming River, at $110 for a switch has certainly proven that cost is no predictor of reliability! And that stupid thing is a mechanically activated switch, making an electrical connection!! Go figure!

Just proves nothing is as simple as it ought to be. I bety if you ask flaming river they'll act all surprised the switch failed and that they sell them by the thousands.
I used to use just a simple little toggle switch on the steering column and i've gotten more fancy in my old age.