View single post by subwoofer
 Posted: 11-24-2014 08:09 am
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Joined: 04-01-2008
Location: Sandefjord, Norway
Posts: 583
Eric wrote:
Tom and Joachim..thanks for the input. I've seen comments that the tach wont work after a electronic conversion and that it needs to get "converted" electronically to be functional again..whatever that means. Others say their tach works fine..any thoughts?

Works(-ish) with Ignitor-II, but I will replace the innards of the tach with a spiyda tach conversion kit very soon. The Smiths RVI tach is kind of special in that it is current triggered rather than voltage triggered - meaning that ALL current to the coil has to go through the tach. No other tach I know of uses this principle, and it is not good for general reliability.

With regard to the resistance wire, I have 12V at the white wire coming from the tach where it attaches to the resistance wire under the dash. At the other end of the resistance wire (at the coil), there is only 8V. My worry would be bypassing the resistance wire would increase the current thru the tach and burn it up. If I bypass the resistance wire, do I buy a coil with a higher internal resistance (3 ohm?) to prevent this from happening?

Sorry if this is all rather basic..Im a newbie to this car.


As I already said, get a Lucas Sport Coil or a Blue Bosch. You won't kill the tach with current, but vibration will kill the tach sooner or later. Get rid of the resistor wire and mount a proper 12V coil. And convert the tach to voltage triggering, it will be more accurate and you remove at least two points of failure.