Wiring confusion

[Joe Schlosser]

We are about to finally start up a 54 100.
However there is a little confusion about the wiring to the coil and distributor.
I have attached a wiring diagram (maybe ) and have darkened in the wire in question, Number 16.
In addition to normal connection between the coil and the distributor it goes form the coil to the master switch in the boot.
Neither I or my buddy the car owner have seen an ignition setup wired like this
Can any one fill me in on the purpose of this wire?
Thanks in Advance

 

[Bob_Spidell]

The wire to the cutoff switch in the boot is a simple anti-theft device. When the cutoff switch is in the 'off' position the battery ground cable is effectively disconnected from the chassis, and the starter cannot run. Also, in the 'off' position the wire from the coil to the switch grounds the coil. Since electrons will always seek the path of least resistance they will flow to ground instead of through the coil, which prevents the coil from producing spark. IOW, in the 'off' position, the coil is grounded, but everything else is not, and vice versa for the 'on' position. So, in the 'off' position, if you hotwired the ignition--frighteningly easy with a Healey--and tried to push start the car it wouldn't start because you'd have no spark.

Note the cutoff switch can be problematic; if all else is in order and the engine turns over but won't fire disconnect the wire to the boot and see if you can get a start.