Blowing Voltage Regulators

[JTQ]

Hello everyone,

My 1966 912 is blowing voltage regulators like crazy. I'm on my 3rd one.

In my de-bugging process I have replaced the battery (new red top Optima), had the generator checked and it is doing it's job and the brushes were in good shape (it's not new so I don't know if a short or other issue in the generator could be the issue).

Each time I replace the regulator the car seems to work fine for a few days then suddenly I end up stuck somewhere with a dead battery. Could the power be spiking for some reason and blowing the regulator? What would cause this?

Wiring is old but appears to be in good condition between the regulator and generator.

The car has petronix ignition with a Bosch 050 distributor. Coil is almost new. I did replace the petronix ignition recently with the correct one. (previous owner had the wrong part # although it seemed to work fine).

First regulator was stock. Second was very similar off Ebay (from a Saab). 3rd one I ordered through an alternator specialist. Slightly different but same inputs and specs. They all worked at first.

Any thoughts would be greatly appreciated.

Cheers, Jeremy

[Jaems Thomsen]

Optima batteries are not the best with a generator. They are better with alternator. If the battery goes dead it will put a strain on the generator and regulator to charge it up and could then burn out the either of them. Also the Optima's are no longer being made in the US and the quality control is not as good as the US made ones.

The regulator should match the Generator. Which means the it should be a Bosch regulator that is correct.

The 050 distributor will not be the problem even though it is not correct for the 912 engine; the curve is for a VW engine. The 022, 031, 061, or the RS0012 are the correct ones.

[Neil '67 911S]

My guess is you have a bad battery. Bring it to wherever you bought it and get it tested.

As far as the 050 goes, the advance curve is different from the 018 and the 022 but the total advance is the same. Since full advance occurs around 3000 rpm, you will only notice the difference accelerating.