Positive ground conversion

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Sideways
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Joined: Mon Oct 03, 2011 12:58 pm
Location: Delta BC Canada

Post by Sideways »

1970 cortina GT wrote:Old, topic but I have another question. Once I have converted my tacho to negative earth is there anything else I need to do to it if I'm using a Petronix electronic ignition? There is a place in NY called Nisonger that suggests there are some other changes necessary? They are looking at $275 US to do the conversion, appreciate your thoughts anyone. BTW I ran an Accuspark electronic ignition in my MK2 and whilst it is negative earth I didn't change anything else in the tacho.
I (vaguely) remember doing the conversion on a '66 Elan as well as a couple of Lotus Cortinas, both '65s and don't remember doing anything with the rev counters to get them to work properly - and I drove using the rev counter back in those days, rarely looked at the speedo!

This http://www.lotus-cortina.com/electric/convert.htm may help - never tried it myself but looks fine at first glance.
1970 cortina GT
Posts: 363
Joined: Thu Dec 05, 2013 7:19 pm
Location: Saskatoon, Saskatchewan

Post by 1970 cortina GT »

Thanks guys, I've seen the positive to negative ground conversion details it's just the electronic ignition installation and associated possible changes to the tach that I was wondering about. Thanks.
Life isn't complete until you have a pair of twin cams in the garage...
Sideways
Posts: 619
Joined: Mon Oct 03, 2011 12:58 pm
Location: Delta BC Canada

Post by Sideways »

1970 cortina GT wrote:Thanks guys, I've seen the positive to negative ground conversion details it's just the electronic ignition installation and associated possible changes to the tach that I was wondering about. Thanks.
Small correction to my previous post, I did have an rev counter issue with a Plus 2 did I did the conversion on but that had an early MSD...I think the information to allow an easy (cheap) conversion is out there, just a question of finding it.
peteleo
Posts: 1332
Joined: Sun Aug 24, 2008 11:57 am
Location: San Mateo,California

Post by peteleo »

Lee,

Electronic ignition won't effect the operation of tach after converting the tach to -grd.
If using MSD you will need to install a tach adapter ( made by MSD Inc. ).
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