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MG MGB Technical - Tachometer parts missing?

Greetings: My 67B has a Pos. Ground Tach. (and electrical system) I am rewiring the car and everything works except the tach.

I have 2 questions:

1. Does the plastic connector on the back of the tach that the white wire loops thru have a metal clip or something similar attached to it? Mine does not....
could that be my problem...

2. Has anyone out there hooked up a modern negative earth tach to a pos. earth MGB ? Is it dooable and any suggestions on what kind will work and how to install it would be appreciated.. I am wondering if the pos. ground will make it impossible???

Thanks
Moe

Moe,
The plastic block has a very small, easily lost metal clip that fits over it. The tach ewill not work without it.

On the second point, that is a good question. I'd like to know, too.
David
David

Moe - Mixing polarity on any car and accessory is unadvisable. The only way to do it is to TOTALLY isolate the accessory from ground and then run the hot wire to the case of the accessory and the ground wire to the power terminal. I think that you can see the possibilities with this kind of arrangement. One slip of anything metal around the accessory produces large sparks and copious amounts of smoke and we all know what happens when we let the smoke escape. My advice in three words is don't do it! Good luck - Dave
David DuBois

You can rewire a positive ground tach to work on negative ground. It amy be possible to change a negative ground tach to positive ground. Best route is to find a used mg parts place that has non-working tachs that you get the metal part from. Mine has the metal shelve around the plastic part and is held on to the tach with a small nut.

Jim
Jim Lema

Hi there,

My suggestion: look at http://www.mgcars.org.uk/electrical

There's a lot of information. About all electrical parts (including theTacho).

Gerrit Edelijn
Gerrit Edelijn

This thread was discussed between 08/10/2003 and 11/10/2003

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.