Technical Car won't shut off with battery cut off switch

I put a battery cut off switch on my car when I built it 5 years ago. I would like to race the car at the local Friday night street car drag races but the track will not let me race the car because the switch will not shut the car off. I took the Alt power wire out of the harness and ran a new power wire from the cut off switch to the Alt and also put a diode in the Alt feed wire that goes to the switch. The car (1956 chevy) has a Ron Frances wire kit and a 3 wire 10SI Alt with a built in voltage regulator.
Any one have any ideas as what I did wrong or what I can do to fix this. If I unplug the Alt and then hit the cut off switch the car dies.
Thanks in advance for any help someone wants to offer.

 

The battery is in the trunk and that is why I have to have the cut off switch in case there is a problem the track crew can shut the car off.

 

You need a 2 position switch that breaks the battery and the alternator feed. Looks like the switch you have with 2 smaller studs. Problem is most guys run the feed wire from the alternator to the plus wire from battery that you have on your starter solenoid. Now it needs to go back to the switch you mounted outside the trunk.

 

Usually people can't get their stuff to start.

Picky picky picky!

 

Here's another diagram that may help. Second set of terminals isolates the charging system.
https://static.speedwaymotors.com/pdf/910-64501.pdf

 

unplug the alternator when you get to the track.

 

Put a relay on the alternator 12v. wire and power the relay from the battery switch. This way when the switch is turned off, the contacts on the relay also open, killing the alternator from supplying power to the car.

 

I ground the alt's ground wire through shut off switch, shut off switch on the battery's ground cable...

 

Killing power to the alternator should not kill the engine you need to kill the power going to the distributor. I was taught on older cars to start it and take the positive off the battery and if it stays running the alternator is working. So are you wanting to isolate the battery or have a kill switch. may be I missed some thing here. good luck with that.

 

It's a Chevy. They don't have a ground wire on the alternator. They ground through the alternator frame.

 

NHRA wants both. They require a battery switch if the battery is in the trunk, and that switch must be readily accessible, and needs to isolate the battery, and kill the engine.

 

I just ran another 8 gauge cable to the alternator from the cut off switch.

First time I went through tech they checked it. They asked to run the engine at a high idle and then he hits the kill switch.

 

just asking why can't you put the disconnect on the ground? so when it's turned off their is no ground and that kills every thing.

 

For what it's worth. If you have an electric fan and it's running when you kill it, it will back feed like a small alternator.

 

Any reason not to just do it this way?

 

Excellent idea !

 

they make a kill switch that the charge wire runs through just for this purpose look at em at summit or jegs they have two big posts for battery and two lil ones for the alt hot lead , common on drag cars ,,work like a champ nhra says ya gotta do it that way ,,
fabricator john
miss you dad

 

Do Not put the switch disconnect on the ground side of the battery. If you forget, and attempt to start the car with the switch off, the system will attempt to achieve ground through your MSD Box or other accessories. All of these items will smoke when 30 amps is drawn through them.

 

That won't kill the engine

 

I put the battery under the hood, no need for a cutoff switch. But that might be too simple of a solution for you.

 

None of those you posted will kill the engine. They may prevent it from starting, but once running they will continue to run. You need to disconnect the positive source from the alternator if you want to kill the engine.

 

the first will cut power to the coil, the second just cuts off power from the battery, and you are correct on that one. The last one cuts power off to the fuse panel, coil and alt
if this is for a 3 wire alt, would this switch wiring work, I can see the issue now for a one wire?
if power is cut from the battery and the coil, can the car still run wired like this diagram?

I think your correct on the 3rd one. read the entire thread the diagram came from, the same comment you made came up.

 

Use this. I have one on all 3 of my cars. I run the battery out to the fuse panel on one side. Alternator into to the battery on the other. It kills everything instantly.

 

like this

currently wiring a truck so Im looking up info.

 

You don't need a fancy 4 post cut off [a simple on-off 2 post will do]
The Charge wire is looping to the ignition keeping it running. A common problem!

You need to run the charge wire from the Alt all the way back to the battery [or the battery side of the cut-off switch.]
For safety add a fusible link to this wire [close to the battery]
If you're constantly working around the Alt [and risk shorting screwdrivers etc] add a decent blocking diode into the charge wire
It will charge but won't discharge

Also by doing it this way, If the battery is cut-off at rpm it will absorb current until the engine stops [preventing damage to the regulator etc]

 

The first one is incomplete, I can't tell what it's doing, and I'm no stranger to electrical schematics and diagrams. And the 3rd one doesn't fully load on my computer, I'm left looking at some scattered symbols, but it looks to me like the alternator is still connected into the mail electrical feed circuit, supplying voltage to the fuse panels.

 

There you go.

 

here is a better pic, the OP was questioned that the alt would keep it running. I can see it on a one wire but wonder on a 3 wire alt.This simple diagram looks like a one wire, so its shouldn't work, Im gonna delete it