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MG MGB GT V8 Factory Originals Technical - The best Alternative, question for the experienced

I'm at the wireing in stage of the conversion and don't know too much about car electrics (I'm having to learn though!). The motor is a '95 3.9 however I've used a '85 front cover and alternator.
The question is that the MG uses three wires (the main battery charger, thick, a brown with yellow stripe (warning light) and another thin brown wire running back to the battery. The '85 lucus alternator from the range rover only has two connections that I can see, the main battery charging wire and the indictator wire. There was brief mention made in the Haynes manual of battery sensing alternators and current sensing alternators which is all news to me. Am I right in assuming that the MG alternator (3wire) is the battery sensing variety and the '85 Rangerover alternator is the current sensing type?. In other words I need to simply not connect the 3rd wire?.

As a possible (& preferable) alternative I also have the '95 "internal fan" 100 amp type of alternator which came with the motor. This seems to be of the 3 wire battery sensing type (with an addittional earth wire). Unfortunatly this has a flat belt style pully. Can this pully be swapped for the V style and still work? or is there an imcompatability of parts or is the V type fan belt simply not up to running a 100 amp alternator?.
Sorry for all the questions but I'm in uncharted teritory here.

Petter, I have wired up a lot of the Rover alt from 68 3500 to the 95 amp. 93-94 rover & I have cut the third wire & taped it up were I just used the 2 wires. I have 1 of the int. fan alt. & I think a good alt. rebuild shop can help with the right pully.
Glenn Towery

Early 5-pin alts did use a thin battery sense brown wire as well as the main charging brown wire. Then they changed to 2-wire system which just had the single brown wire (although these were probably 3-pin alts with one of the two big output spades unused) and at the end went to 3-wire system which used two thick brown charging wires to double current carrying capacity. It is the alternator that needed the sense wire, not the car, so if you use an alternator that doesn't need it you can tape it back at both ends.

If '95' means the year it is more likely to have two large output spades rather than an output spade and a sense spade, and for best results both should have thick browns back to the solenoid or wherever.
Paul Hunt

Many thanks to you both.

This thread was discussed between 13/12/2002 and 15/12/2002

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