Install of master shut off switch

Hello, my car has the master switch mounted on the seat riser , 31 roadster, the cables come up through the curtain panel,with grommets around them, and it controls the ground. I do the ground connect on other cars too , if it should short some how it will just make a connection. Hot lead will spark when coming into contact with ground.
 
GD, my master location is identical to yours. If you cable it just like post#19, you will be ok.
 
So, how would I wire this photo to have the master turn the car off when it's running?

The photo is what nkaminar helped me with, and it has worked great.
 

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You would need a more elaborate switch with more terminals to shut the ignition off with the master while running.With a stock A the master takes the battery out of the circuit when shut off.If you kill that switch while running the generator will just keep producing,making up to 40 volts.You'll know it,you'll get some pretty spectacular backfires with 25 or 40 volts is put to the coil.What's the reason for wanting to kill the ignition with the master?
 
old31 said:
So, how would I wire this photo to have the master turn the car off when it's running?

The photo is what nkaminar helped me with, and it has worked great.
Click to expand...

Generally you would want to turn the car off using the ignition switch.
 
Years ago I bought a FOUR POSTED (Two small & Two Large)SHUTOFF because I read that was what was installed in RACE CARS . What is supposed to happen is ALL ELECTRICAL POWER is SHUT OFF in case of an emergency !

ANYONE ever install one on an "A" AND HOW is it connected ?
 
Cape Codder said:
Years ago I bought a FOUR POSTED (Two small & Two Large)SHUTOFF because I read that was what was installed in RACE CARS . What is supposed to happen is ALL ELECTRICAL POWER is SHUT OFF in case of an emergency !

ANYONE ever install one on an "A" AND HOW is it connected ?
Click to expand...

The reason they use them on race cars is safety concerns in the event of a crash. You want to be able to cut all power everywhere in the car to reduce fire risk. To use one on a Model A, you would route the battery through the large pair, as usual, and then modify the black wire from the terminal box to the coil so that it instead goes first to the cutoff and then to the coil. Cutting these two will cut power to the coil, which will kill the engine within a few seconds.
 
I installed my batt cutoff on the firewall, up and to the left of the steering column. Switch lever is on the inside of cab. Due to a previous owner boring a hole there for some reason. Since I have multiple ground wires, I opted to add the cutout to my positive batt cable. I also have everything changed to 12v. negative ground. Works great no problems so far.
 
The reason I asked was just in case there was an issue with the switch I could use the master to turn it off.

Like others I read that race cars had the master to do that, but I did not realize that it was a 4 post master.
 
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