Tach / alternator change

[jk952]

I was thinking of putting in an alternator in my S2 which normally would have been a positive earth (ground) - I noticed the tach states "positive earth" on the face - does anyone know if there is a problem switching to negative earth as the alternator requires?
If asked before - help direct me where...


Jack

[stugilmour]

Jack, this link describes the changes required for an MGA with a similar RVI tach. There are several pages to the article; click on the green arrow at the bottom of the page to flip through the various pages. I used this and related articles on the site to open up my tach and adjust it, so in my case it was similar to the Lotus. Basically appears to be two steps; (1) changing the sensing loop direction and (2) changing the power and ground leads inside the tach. Note I have never done the polarity change, but this should get you started.

Hope it's warmer in Ontario than out here!

http://mgaguru.com/mgtech/electric/et202a.htm

[paddy]

See also this this thread:

elan-f14/pos-neg-earth-t17257.html

and the link to the cortina site in there.

I think before you do anything you should also decide whether or not you will be using electronic ignition, because this affects how you deal with the tach. There are countless discussions on that particular issue:

http://www.lotuselan.net/cgi-bin/search ... oom_sort=0

The bottom line is that if you are going to be using electronic ignition, then you will most likely need to convert the tach to RVC or electronic. It seems that sometimes a conversion isn't necessary, but it's usually needed to stop the tach from bouncing.

Paddy

[jk952]

Thanks for the info Stu and Paddy, I'm glad I asked.

..and it's hovering around freezing with the odd day above enough to get one enthusiastic for spring! Inuslated garage with heat obligatory. Think how dull it would be with 365 livable days a year further south.....

Jack