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MG Midget and Sprite Technical - Positive earth - advantages?

Hi

Is there any advantage to staying with positive earth, apart from being able to use the dynamo powered mechanical rev counter and such 'originality issues'?

My reason for asking is that I am thinking of rewiring my Mk2 948cc Sprite and the conventional wisdom is to switch to neg earth, as this enables a switch to alternators which have higher power outputs. But what if you can switch to a positive earth alternator, such as: http://www.amp-starters.co.uk/product.asp?P_ID=12727 I recognise higher cost and replacement issues compared to a standard Lucas neg earth model, and loss of rev counter drive, but any other issues for a positive earth alternator conversion compared to going neg earth?

Thanks
Mike
M Wood

No
Onno K

Just changed mine after many years of reluctance. You don't need to replace anything unless you have some specific +ve earth stuff (electronic ign etc).
No disadvantages but lots of advantages , e.g much cheaper electronic IGN, Radios, AUX power sockets etc.
This article tells you in basics what you need to do.
Ed

http://www.spritespot.com/Downloads/Positive%20to%20Negative%20Ground%20Conversion.pdf
Ed H

What are the advantages of Positive grounds

They make spectacular fires ...when you add in a neg earth accessory

I got marshmellows and hot dogs

Prop
Prop and the Blackhole Midget

There's no difference between +ve and -ve earth as far as the vehicle itself is concerned, so for reasons earlier in the thread the advantage is on the side of -ve earth.

Don't forget you need to mod or change the rev-counter, unless you have cable-drive version; plus you'll need to swap the connections on the coil, so the spark travels the correct path (centre of plug to body...).

A
Anthony Cutler

-ve earth is supposed to reduce rusting, I forget exactly why. Its something to do with the whole car acting as an anode when it is +vely charged.

Not sure that the evidence with cars in use really bears this out though. There seem to be as many badly rusted floors on the later cars. Though maybe that was due to poorer quality steel being used in the latter days of BL when they weren't paying their suppliers promptly.
Guy W

The real driver was the advent of semiconductors/electronics. it's no coincidene that most switched to negative earth at about the same time as alternators became common. Not to mention the radios etc all went to -ve earth as well, so to avoid lots of Prop's marshmellow there wasn't much choice ....
Paul Walbran

I agree with all of the above about going neg. but personally see no need to switch to alternator unless you are running loads of extras.

Trev
T Mason

This thread was discussed between 27/09/2012 and 28/09/2012

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