Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Positive to negative, pros and cons

Good luck Ben and don't forget post pics and tips as you go along.

Here's one supplier of alternators which resemble dynamos- but I'm sure there are others.

http://www.autoelectricsupplies.co.uk/product_list/197

That looks like a great source. I see that there is a regulator built in and I assume also a rectifier as the output would appear to be DC. Saves a lot of hassles.

I would imagine that you would also need to change your starter motor and possibly the wiper motor unless it is possible to run in either positive or negative earth. Another item to check would be the fuel pump if it is an electric pump. If the wiper motor and fuel pump are two wire, positive and negative, you would have to be very careful to change the connection correctly.

PS. I wondered if I was correct in thinking that the starter motor would be polarity sensitive. Perhaps that is not the case. I found this site which refers to changing polarity on an MG A. http://mgaguru.com/mgtech/electric/et202.htm
It seems to be a good guide and also mentions the electric tachometer and the heater fan. He has quite a bit of information on the electric fuel pump.

I also forgot about the ammeter which would have to be wired the right way round.

Ben,
My 59 and 61 Plus Fours are both positive ground, but I'll probably change to negative when the generators fail and I replace them with alternators.

Peter pointed out an important consideration: the ammeter also needs to be rewired. The ammeter is in an awkward place under the dashboard and it must be wired and insulated correctly. A friend of mine did not get the insulation right when he converted to negative, and it actually set off a small fire and necessitated a new wiring harness. A surprising amount of electricity goes to that little gauge.