part 2 alternator not generator

Here’s where the extra safety comes in: We add a fusible link to this master charging wire. A fusible link, as the name implies, works as a fuse. If anything goes dramatically wrong, the fusible link will sacrifice itself and melt away, effectively saving the more expensive components. Once we have selected our main charging wire and fusible link, we use the original wiring setup as a guide to install them–usually from the alternator to the starter solenoid.

Assuming we can get our hands on a multiple-wire alternator, the next part of our wiring job is to make the dashboard’s idiot light work properly. This usually takes a little research, but most multiplewire units work by becoming “excited” with external voltage.

One side of the idiot light is linked to the alternator, while the other side is linked to positive 12 volts. (Technically, the voltage is closer to 13.5-13.8, but we’re sticking to the nomenclature of our nominal 12-volt systems.) When the key is in the On position and the alternator is not working properly, a ground condition occurs and illuminates the idiot light to indicate a problem. When the key is on and the alternator is operating properly, the alternator sends positive 12 volts back to the light, extinguishing it.

To deliver the necessary volts, we run an exciter wire between the alternator and the idiot light; on Lucas systems, this is usually a brown wire with a yellow tracer. If a car features a voltmeter or ammeter, however, no wiring modification is required to get the idiot light working; these gauges can usually pick up their signals downstream of the alternator wiring.

Our last step is to deal with the now-abandoned OEM wiring. When it comes to this task, there are two good choices and one bad one. The bad one is to let the wiring hang and potentially short out. A better choice is to disconnect the wires, then tape and hide them. We do this if we think there is a chance the car might return to the OEM configuration. After all, we wouldn’t want to complicate the process by cutting off the wiring components.

The other good choice is to completely remove the wiring from the loom so it doesn’t create any risk or confusion for anyone in the future. This usually requires cutting apart the loom’s outside wrapping and then rewrapping it, which is no trivial task. It does make things neater, however, so we often take this route.

All Good Things Take Time

We originally stated that most alternator conversions are bad news. However, we also showed you the proper approach to making your swap the exception. Doing things correctly will take additional fabrication, wiring and time, but the results will be worth it: You’ll end up with a safe, long-lasting and easy-to-service conversion.

Step 1

Alternators require a solid mount to prevent vibration-related damage. After making some quick measurements, we roughed out a mount from some 1/4-inch cold rolled steel.

Step 2

After some more measuring, cutting, welding, drilling and test fittings, our new beefy mount was starting to take shape. We just needed to give it a clean look with some grinding and painting.

Step 3

Put enough paint on it so it doesn't look like you just took it off a junk car.


Once we cleaned up the edges and applied a fresh coat of paint, the mount was ready for installation.
Hold mah beer and watch this! Don't buff off the crud. Suck a few more beers instead.
Better yet is to mount it before the paint dries so it will scratch it and prematurely rust.
Then you can say "Ah hate it when it does that....." and then do another crude install, you butthead!

Step 4

Instead of using an OEM sliderstyle adjuster, we fabricated a nicer component using a pair of rod ends and coupler sourced from McMaster-Carr.