master shut off with magneto

the nhra rule book said that you have to have the master shut off in the rear of the car kill all the electrical components and the magneto. my question is how do you rig it up cause you have to kill the battery power on the positive side and you kill the magneto by grounding out the positive side of the coil. so how do you guys make this work

 

Flaming River makes a master switch for mags with the extra posts for the mag ground, a little pricey compared to a straight master switch but is the simplest way. A cheaper way is to use a relay although its been so long since I did that I really can't remember exactly how I had it wired. Maybe someone here can help.

 

I would recommend this one...(edit:as did the gentleman just above me!)

http://www.flamingriver.com/index.c...tegory_id=133/home_id=231/mode=prod/prd61.htm

 

you know.....i was thinking this very thing a few months ago. so, i got on the phone to my division tech guy and asked him that very question. i said...i have a blown 23T with a mag, and a small alarm battery for my shift lite and tach. on this master cutoff switch deal....what do i need? he told me this.....you only need a master cutoff if you run a battery ignition, and what do you think would happen if you hit the mag kill switch with the motor revved up? point taken i said. i can't say that i have ever seen a master cutoff, or kill switch on the back of a TA/FC or T/AD. i would call your division tech director....just to be safe.

 

I got one of those "trick" master cut-off switches with the mag switch kill and it didn't work, so I went with a relay instead.

The way it works is with the master cut-off in the off position, the relay sets its output to ground which is connected to my mag cut-off switch. With the master cut-off in the on position, the relay sets its output to nothing so the mag is now armed which can still be killed with mag kill switch.

The relay works with up to 40 amps continuous and I paid less than $30 for a set of 3.

Btw, if you hit the wall and get knocked out with the motor zinging, that master cut-off will come in quite handy for the safety crew.

 

What your telling me you would be scared to walk in front of the rear tires of a car and reach inside to kill the mag while the engine was turning 10k

 

Oh yeah, scared poopless!

 

its simple
http://www.msdpromag.com/pdf/8134_killswitch.pdf
I switched the hot side not the ground

 

do you have any part numbers of the relay your talking about

 

I'll do even better, here is a link to the relays on EBay.

I also used the same relays for neutral safety-switch and on-board starter relay so that each switch never gets the full amperage, they just toggle the relay and relay handles the loads.

Good luck,

 

Kill switch

http://www.flamingriver.com/index.cf...prod/prd61.htm
I have a new one of these $75.00 plus the ride. PM if interested.
Mark