Immobilizer / Anti-Theft / Kill Switch

[patrickt]

Originally Posted by cycleguy55

Nothing that I can see in my instructions that specifically identify a switch other than the ignition switch. The only logical place to connect a switch would be in the circuit from the ignition switch (small red wire). Cut that and route it through the kill switch to kill the MSD input from the ignition switch.

Best place to install the switch? Under the hood? Under the dash?

The MSD instructions show you that grounding the white wire, or purple wire, through a switch will act as a kill switch (the color depends on how your distributor is installed). It's simple and easy.

[cycleguy55]

Originally Posted by patrickt

The MSD instructions show you that grounding the white wire, or purple wire, through a switch will act as a kill switch (the color depends on how your distributor is installed). It's simple and easy.

Not in 6AL instructions. If you can find it you're a better man than me. https://documents.holley.com/6425.pdf

I'll check the instructions for some of the other MSD boxes.

Edit: Found the reference in this document, which supposedly also applies to 6AL. Seems odd this isn't in above-referenced document if it applies to 6AL. https://documents.holley.com/6430.pdf

THEFT DETERRENT
The MSD provides the opportunity to easily install a theft deterrent kill switch (Figure 4).
White Wire Trigger
When using the WHITE wire to trigger the MSD, install a switch across the magnetic pickup VIOLET wire to ground. When the VIOLET wire is grounded, the vehicle will crank but not start.
Magnetic Pickup Trigger
When using the mag pickup to trigger the MSD, install a switch to the WHITE wire and the other side to ground. When the WHITE wire is grounded, the vehicle will crank but will not start.

[patrickt]

You know I remember that now, it seems MSD included the instructions in some instruction sets, but not in others. Anyway, it will work. Try it.

[cycleguy55]

Originally Posted by patrickt

You know I remember that now, it seems MSD included the instructions in some instruction sets, but not in others. Anyway, it will work. Try it.

BTW, I totally agree most of today's criminals would have a problem with a Cobra: 1) manual transmission; and 2) carburetor instead of fuel injection - especially if a cold start.

My ignition box is actually a Summit Racing box, supposedly built by MSD. The MSD 6AL and Summit instructions are almost exactly the same, so I'd expect the kill switch wiring would work the same way, but I've reached out to Summit to confirm. Thanks for the info, BTW.

Not asking you to give away any secrets, but - best location for switch?

[patrickt]

Originally Posted by cycleguy55

Not asking you to give away any secrets, but - best location for switch?

Anywhere that is easily reachable under the dash, while you're sitting behind the wheel, and doesn't draw attention to the fact that you're doing it.

[1795]

My ERA had a battery disconnect switch in the trunk near that battery. It was keyed so that you could take the key with you and attach it to your key chain. Since the trunk would be locked it would also be a deterrent.