Tach help please

[rdssdi]

I had my Smiths tach converted by Nisonger (USA) to work with an electronic ignition.

I was told to connect the pos+ wires together and run the tach in series with the neg- side of the electronic ignition.

I had problems with my distributor and the luminition stopped working when the distributor was on the bench. A new pertronix was installed. The distributor rebuilder said to hook up ,the distributor directly and leave the tach out of the loop.

I am trying to find a way to hook it up with out placing it in series with the neg- side of the ignition system.

It has been long since I wired the tach and cannot remember the old nor new connections. I do remember that the original system used the pos+ side of the coil. I assume in series with the coil. Does it have to be the same with the negative side?

Where does the tach get its power?

Does anyone have a link or info on the rear of the tach and what all the connections are?

Thanks

Bob

[Frank Howard]

I had my Smiths tach converted by Nisonger (USA) to work with an electronic ignition.

Bob,

Nisonger sold me a new Smiths ammeter, fixed my combo gauge, and fixed my speedometer. No problem. Nisonger also converted my tach. Nothing but problems. I sent it back and they claim they did something with it. It didn't work. I sent it back again. This time they told me that they had neglected to give me instructions as to how to hook it up because the hook up was no longer the same as before. It still didn't work. I sent it back again. It still didn't work. I asked for a refund. My request was ignored. I wrote to my credit card company. They retreived my money from Nisonger. I finally did the conversion myself.

From memory, I can tell you that the tach gets it's power from a green 12V wire behind the dash. I can also tell you that I did hook the two white ignition wires to each other and ran a new wire from my converted tach directly to the negative side of the coil. This wire was not in series. Hope this helps.

[tdafforn]

an updated smiths tacho (from the 80s) comes up for sale on ebay periodically.
you can then convert simply by swapping the internals and perhaps a slight modification of the outer can to allow the connections through
Tim

[rdssdi]

I have sorted this issue. Apparently Nisonger has modified the tach to function with an electronic ignition. Their modification changes the tach to read the negative impulses rather than a signal from the positive side as original. It remains a "loop system". The tach must be wired in series with the negative side of the coil.

In order to utilize the negative side of the coil only the tach must be converted to new inner workings. I believe a stepper motor is used. This "one wire" system would not require it be wired in series with the ignition system.

I have it wired in series and all appears to function. I will have the tach converted and rewire accordingly as time permits.

Bob

[cbguerrajr]

Bob,

I had Nisonger changed my tach to neg ground and coverted to elec ign.
I still have the points in the distributor and the tach works well with the original setup.

They added a new wire coming out of the back of the distributor which connects to the coil, I'm pretty sure it is in parallel, not in series.

I still have the instructions from Nisonger for wiring. If you want, I can scan and email.

Carlos Guerra

[rdssdi]

Carlos

No thank you.
It sounds like you have a single wire hook up. It is my understanding that the tach conversion to the new stepper motor type will work with one wire from the negative side of the coil with either points or electronic ignition.

My tach was modified rather than converted to the new system. If they would have explained this difference to me I would have chosen the change to the new system for its reliability and ease of hook up.

Bob