JUST RELAX and breath….. Some people make this job look difficult when it is really simple. That is because they get busy telling you how to modify things their way, and usually forget to tell you how it actually works. When you know how it works, you have more freedom to do it your way. An alternator is an electrical device which generates alternating current by changing mechanical energy to electrical energy. Alternators are cheaper and easy to find compared to their counterparts — the generators — and therefore more preferred in vehicles. Converting from a generator to an alternator is a task that may requires the vehicle to change from positive to negative ground as an alternator will never work on a positive ground state.
Each car manufacturer uses differing wiring plans so obtaining a wiring plan will be very helpful in converting from a generator, but for our purposes we will keep it simple so that you can see that this project is not necessarily all that difficult for the DIY project. There are also kits available in the aftermarket to help in making this conversion.
Switch off the engine of your vehicle and disconnect the clips of both the negative and positive terminals of the car battery. Turn the vehicle battery 180 degrees and connect the cable leading to the starter to the positive terminal of the battery under positive to negative ground conversion. Do not connect the negative terminal as you will have completed a circuit and electrical accidents are bound to occur.
Remove the cover of the dashboard to get to the ammeter if your classic car has one. Reverse the wires on the back side of the ammeter to connect the negative to positive terminal and vice versa for negative ground conversions. You will also need to change the voltage regulator usually located in the engine compartment near the battery.
Reverse the connections on the ignition coil as this helps in preserving energy in the coil for negative ground conversions. The ignition coils terminals are usually marked with SW for switch and CB for contact breaker and hence will not be difficult to locate.
Disconnect the generator and remove it from its place of attachment. The alternator usually has a shorter length than the bracket of the engine and therefore you will need a metal tube equal to the difference in length between engine bracket and length of the alternator is mandatory to make the alternator fit in place. Fix the alternator and the metal tube tightly using bolts and perform the connections on the alternator exactly how they were on the generator. When mounting your new alternator, be sure attach it securely to the engine. If the tail end of the alternator is weakly mounted and left to vibrate it might eventually fatigue and break one of the mounting ears on the alternator, and a broken ear on the case may not be a valid warranty exchange. Even worse, some replacement water pumps now have an aluminum casting, and the generator mounting ear on the water pump is notoriously weak and prone to break with the slightest disturbance.
For those of you who want the classic car look, but still want an alternator power there are now alternators that look like the classic generators which will alleviate some of the added change over work.
Remove the old belt of the generator and install it with the new one as the alternator pulley is generally smaller.
Check again to verify everything is switched off. Upon completing the check-up, reconnect the negative terminal of the car battery and switch on the ignition switch to verify everything is in order.
Each car has differeing wiring layouts and some additional steps; we also recommend adding a main line fuse to avoid any major damage due to a system short. The good news is that for most classic cars converting from a generator is a DIY project that will upgrade your vintage car’s electrical system especially if you are looking to upgrade the ignition system as well.
I don’t see why an alternator is preferred over a generator. I had a 1969 VW Beetle and my battery gave out while I was driving to Alaska. The only worry I had was finding a place with a decent slope so push starting it would be easier. If it was an alternator system, (and if it was a *gag* automatic transmission) I would have never been able to start it without sufficient charge in the battery. I bought a battery when I got to Alaska, but I could have carried on longer if I needed to.