Classic/Antique Car Repair: Lucas Generator, amp generator, measure charge

Question
Hi.
I have a french car Facel vega with an original Austin healey Bj8
3000 engine,Lucas 42 C 30 amp generator and lucas regulator.
The car had charging problems so I replaced the regulator with a
new RB 340 (NPC 133) 30 amps Lucas original regulator.
It still doesn't charge and the light stays on even if it diminishes
slightly when reving up the engine.
The car is positive ground.
When I jump F and D on generator and measure charge ,this
charge is varying with the engine rpm past 35 volts but it shows
negative(-)  on the voltmeter ( connected red + to the
Generator
jump and black - to the negative of battery.)
What is happening ?
I think I polarized the generator correctly by jumping the F
connector on gene to the - of bat. ?
Can you help me /

Answer
Hi Jean,
Lucas generators can be Positive or negative ground by polarizing.
Let’s start from scratch the way I used while working in dealerships.
First remove the belt off of the generator and remove both wires from the generator and get two wires as test leads that can reach from the generator to the battery. Get a 12 gauge wire for the Armature wire. Keep the two leads you removed so they don't contact each other or anything else. Connect the two test leads to the generator.
Connect the two test leads together. Touch the end of the two leads to the (-) (hot) post of the battery and hold it on for several seconds and watch the generator pulley. It should run like a slow electric motor in the direction that the engine runs it. If it just tries to run but don't, with your free hand give it a spin in the correct direction to see if it will keep running. Do this several times to be sure the generator is polarized correctly to the positive ground system. Some mechanics will tell you that it only needs to be done once but I seen a mechanic in our shop who made it a habit of only doing it once, melt down a wiring harness because of his "Only Once".

Over the years I have run into several generators that could produce very high voltages. In each case the fields were shorted or the armature wires were shorted together. I had one that produced 85 volts and would shock you if you contacted the wire.

Normally the Lucas generator can only produce about 15 to 18 volts full fielded.

The next test is connect the belt back up and be sure to adjust it tight. With your voltmeter connected across the battery start the engine and read battery voltage then touch the two test leads that are connected together to the hot post on the battery (-) and set the RPM at a fast idle. Don't leave the test lead touching the post for more than it takes to read the voltmeter. If you see much more or less than 15 volts you have a bad generator and you can't test the regulator until you correct the generator.

I don't like to do any of the tests at the regulator because there are other factors involved that can give you a false reading. The tests from the generator directly to the battery are exact and final.

Let me know.
Howard