Magneto interference and relay grounding for shutting off

I just picked up a Ronco/Vertex magneto for the DeSoto hemi. I'm going to send it out to Spud @ Fuel Injection Enterprises to have it gone through and checked before I put it in, for advance and all the fun stuff. This is the first mag I've run, and I was wondering about electronic interference on the street. I have a set of electronic '54 SW Wings gauges, well the oil pressure, water temp and fuel gauges are electronic. Will the mag interfere with these working? As for plug wires, I was going to pick up either some solid core lacquer braided 7mm or Packard 440 wire from The Hot Rod Company, just have to get the hemi insulators and ends worked out.

For shutting the engine down, I was looking into using a normally closed relay to ground the mag. The dash on the '32 is minimal with only the gauges and the '40 Ford light switch, don't really want a toggle sticking out but I guess I could hide it. How dependable is the relay method? The main ignition switch in the car is an original '32 column drop/ignition switch. Just trying to plan everything out before it gets here so I have a plan of action when it's ready to go.

Engine is pretty stout, 10.5:1 compression, ported 330 heads, Solid Roller .550 lift cam, Weiand 4x2 intake... I've heard having the mag on a switch is easier to get the engine going before flipping the mag on to fire it.

Thanks fellas!

 

the mag on my harley wreaked havoc with the electronic wideband O2 i use for tuning... went to radio shielded wires on the sensor and everything was fine.

as for me, when it comes to what is gonna shut down my engine as the vehicle is plummeting me towards doom, i like dead simple... no relay... just a mechanical contact to ground... not even a switch. a metal tab that grounds.
im not saying the relay wouldnt work well... i just like dead nuts reliable simplicity.

 

I hear what you're saying. Just a metal tab eh, pretty hardcore!

Yea, I have to use an electric fuel pump now, I lost the cam eccentric for the fuel pump drive with the roller cam. I don't really want to use a pressure switch since you have to build pressure before the pump even kicks over, but it may be a good idea as an interrupter to get the mag cranking before it fires.

 

the tab i use is from a 60s harley wr.
my uncle's FED had an identical tab... basically a momentary switch/contact to ground.

 

Hmm I'll have to look into it. Thanks

 

Tried looking into the interference issue more and no one has a straight answer really. Some say it'll be fine, other's say it'll be outta wack.

 

and the bitch of it is, they are both right..........

 

No radio here, just the basics to get the car to work, lights, gauges, fuel pump. On the hemi the oil pressure sending unit is near the mag, so that may be a potential problem, and the water temp sender is in the intake manifold, again, near the mag.

Would this shielded wire work for the gauges? Or will the steel shielding act as a conductor?



I have all cloth braided wire throughout the car and want to try to keep it all that way. Yea, picky I know.

 

Anyone else have real world experiences?

 

don't nearly all (if not all) conventional ignitions and/or high energy systems use radio suppression wires or plugs when used with sensitive eletronics? (i'm just assuming they do- don't know for sure)

i know every mag i've run was specifically non-resistor plugs, non suppression wires...
i start my harley in the garage and the garage alarm pad does weird things, WB O2 would wig out and the wife bitches about the noise. pretty sure the mag has nothing to do with that last part, though...

 

1954 gauges are electric, not electronics. I have experiance on magneto engines and electric gauges and back then we never considered this to be a problem and there wasn't.

Same with real cooper core wires. not a problem with electric gauges.

Why use a relay? Just have your shut off switch go to ground, preferably at the engine. eliminate a potential failure point.

 

EXACTLY what I was wanting to hear! Someone who has actually done it. As for the wires, should I stick with the copper core? Every site I have seen like Vertex, Cirello, Joe Hunt, all say not to use a suppression spark plug wire and non resistor plugs, which I never use anyways. Thanks for the heads up guys!