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MG MGB Technical - tach problem

My tach quit working shortly after I put an electronic ignition on the car. it worked sprodically then not at all.

I dont know if they are related, or if the problem developed separately. I found a site on the web that recommended removing one of the loops in the tach unit, and i did that to no avail.

Any suggestions?

What year is your car?, on my 79 I connected the white with black stripe wire that runs from the rear of the tach to the negative terminal on the coil and the tach, she started working. I am running a petronix flamethrower coil and ignition.
Peter Murray

72 and earlier cars used a current-pulse triggered tach (RVI on the face-plate) and these are known to have problems with after-market electronic ignition. 73 and later tachs (RVC on the face-plate) are voltage triggered and should be OK.

Sounds like you have the earlier type if you have removed a loop, that is normally to correct over-reading, I think. Check the 12v and earth supplies to the tach with a voltmeter, and make sure there isn't an alternative path to the ignition that bypasses the tach. Other than that it could either be a problem with the tach internals or the electronic ignition - even though the engine runs.
Paul Hunt 2

This thread was discussed on 10/04/2008

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