QuestionQUESTION: i have a 1961 MG MIDGET
i just rebuilt the engine and got a new wire harness.
what is the volts at idle?
i have positive to positive and negative to negative. is that right.
are can call me or e-mail me
ANSWER: Hi Jose. All Midgets up to 1967 are wired for positive earth, so you must connect the battery + terminal to ground. All measured voltages will be negative.
At idle, the dynamo will not generate enough voltage to charge the battery, so the red ignition light should glow brightly. The voltage at the `D' terminal of the voltage regulator will be very low, possibly minus eight (-8) volts, but the actual voltage is not important. When you raise the engine speed to 1,500 rpm the red light should go out and the voltage at the `D' terminal should be between -13 and -15 volts.
---------- FOLLOW-UP ----------
QUESTION: do i have to anything if i change earth to positive? do i have to do anything to the generator? because know i have ground to earth. if so what do i have to do?
AnswerHi Jose. You are not changing anything. Your car was originally built with positive earth. (This can be a problem if you wish to fit a modern radio).
Sometimes, if you buy a replacement generator, it will be polarised for negative earth. To change it to positive earth, all you have to do is this:
1) With the generator fitted to the car, disconnect the wires from both terminals (thick and thin wires). Be careful not to touch anything with them, because they are live.
2) Momentarily, touch the thick wire to the thin terminal. There may be a small spark. That is OK. Traditionally, we touch it 3 times.
3) Re-connect the wires to the generator.
The job is finished. You have now polarised the generator for positive earth.
