Treading on Positive Ground,
or Updating the Charging Circuit on Your Early Jaguar

The conversion to negative ground is trivial; turn the battery around, switch the wires on the coil and on the ammeter. Re-polarize the field coil (skinny wire) on your generator with a zap from the positive terminal of the battery. You are done. As I was replacing the generator anyway, I didn't bother changing the polarity of the field coil. Actually getting to those wires on the back of the ammeter can be a bit tough. It might be easier to change your mind and think "C is bad, D is good."

Converting to a modern alternator, while not trivial, was fairly simple as well. I stopped by Pacific Auto Electric in Sunnyvale (BIG TIME thumbs up on these guys. They really know their stuff.) with my generator in hand and told them what I wanted to do. Less than 15 minutes later I had a Delco-Rhemy self-energizing alternator with a triple pulley (model number when I find it), and several spacers and adjustment arms to play with.

The last slot in the pulley matched perfectly with the old generator, and only a small amount of shim work was needed to fit the alternator in the old bracket. The adjustment arm I used is about 7 inches long, has a curved blade, and is out of some kind of American Ford. A small amount of grinding was necessary to provide clearance for the cooling fan.

The alternator has a built-in voltage regulator, so the RB310 was deleted. I connected the single wire from the alternator to the wires which had been connected to the "B" (battery) and "D" (dynamo) posts on the voltage regulator. The wire from the "F" or field post was taped over and buried in the harness.

This conversion could be a bit more challenging on those later cars (S-types) with power steering pumps hooked to the back of the generator, but a little creativity is required in any conversion.