Drag Racing Discussions > Gassers
I need your help- Magneto kill switch circuit
58Apache:
Ok, So here is what I have. I will have a Mag kill switch in my cab on my switch panel, but then I will need another Kill switch at the back of my truck for emergency shut off. I was thinking of a series circuit. Hot side of the coil to the positive side of the kill switch in the cab. Negative side wire from that switch to the back switch hot side, and negative side of the back switch to motor for ground. This way if either switch is switched off it kills the mag. Any thoughts?
hotrodpete:
You could use a FR1010 flaming river battery diconnect switch with mag kill. You need one anyway so if this fails at a track you have a better chance of replacing it.
lake_harley:
--- Quote from: 58Apache on February 20, 2020, 08:13:07 PM ---I was thinking of a series circuit. Hot side of the coil to the positive side of the kill switch in the cab. Negative side wire from that switch to the back switch hot side, and negative side of the back switch to motor for ground. This way if either switch is switched off it kills the mag. Any thoughts?
--- End quote ---
If you do the series as described I don't believe it would work as intended. With what you described, if you flip the cab switch to kill the engine all you'd be doing is sending voltage to the rear switch and with it still "open" the engine would continue to run.
I'd say the two switches should be "parallel", with the coil wire going to the "hot" side on both switches with the negative sides going to ground. With that, if either switch is flipped to kill the engine, the coil's current would go to ground and kill the engine.
I'll admit to having no experience with a mag in a drag car, but I believe I understand the kill switch process. If I'm wrong, someone PLEASE correct me and I'll crawl back under my rock.
Best wishes.
Lynn
Paul New:
I’ve used a NC contact with a relay years ago. By powering on the battery switch on it will open the contacts and when you de-energize the relay the contact closes grounding out the mag. What kind of mag will you be running?
THE FRENCHTOWN FLYER:
What Paul said. Use a relay in the cockpit switch circuit.
BTW The 4-pole master shutoff by Flaming river and others has much less current carrying capacity on the two magneto terminals than the other two terminals. I have had those terminals go bad.
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