Installed Pertronix now tach doesn't work

I've put the Pertronix Ignitor in my past TR's and B's, but they've all mechanical tachs. I just put a kit in my Sprite and now the electric tach doesn't work. It's pretty simple wiring, but as a mechanical guy, I'm kinda stumped on this.

Car is a '66 Sprite, with a DM2 dizzy (I know, not original) and positive ground. Followed the pos-grnd directions and car runs great but tach sits at 0.

I sent a message to Pertronix support and received a question back as to what car, but nothing since (been almost a week).

Original circuit: switch => tach => coil, coil => dizzy => grnd
New circuit: switch => tach => Ignitor(dizzy) => coil, coil => grnd (per instructions)

Any ideas??

I believe the tach needs to be connected to the output side of the Pertronix unit. The way you have it currently connected the tach will never see the Pertronix output pulses.

Rick

Rick -
Agreed, but I followed the wiring diagram supplied by Pertronix. I'm thinking I'll just put the points back in so I can use the car and shelf the Perronix....

You don't need a tach to drive the car. Its an option in most other cars.
Pertronix changed their modules this year and there has been a rash of non-functioning tachs because of the change. They developed a way to build a stronger signal to help overcome RFI noise, but it results in problems with current sensing tachometers like yours. Cranecams.com has instructions on how to overcome it. Look up the installation instructions for the XR-700 ignition on ther site and read the Smiths Tach troubleshooting information. It IS repairable and not too difficult.

Jeff, how would I know when to shift without a tach? :)

Seriously, thank you for the reference to CraneCams! I will try that tonight and see if ti works. The response from Pertronix was to reverse the loop on the tach - but that would make it a neg earth setup and not pos earth...

I'm kind of a purist (except for things like points replacement!) and like to have the tach working as well as the correct electrical polarity set up.

Thanks again for taking the time to respond!

Brian

I know that this thread is a bit out of date, but on the off chance that you, Brian, have not resolved the problem I would like to relate the following situation. I too bought an ignitor and installed it as per the letter of the instructions. The car started right up and I had no problems with one exception. When I went to turn off the engine I noticed that my tach was not working. I looked on the web and did not find anything that was particularly inspiring. I called Moss, there is a very knowledgeable guy there, Kelvin, who is just as nice as he is experienced. When I installed the ignitor I removed a connection on the coil, + side, that had two wires attached via a female spade connector, both wires were white with a black tracer. Kelvin suggested tha it be placed on the negative side of the coil. The theory involved was solid, but I won't bore you with it. The only available spot on the coil, neg. side, was a female spade. I made a 2 inch jumper with a male spade on each side and connected the two white with black tracer wires to it. This results in the coil having the following connections. On the pos. side there is a red wire from the ignitor and a white wire from the harness. On the neg. side there is a black wire from the ignitor and two white with black tracer wires from the harness. The ignitor works well, and my tach is now working as well. Hope this helps, and of course many thanks to Kelvin.

It was a good day. Hope yours is as well.

regards,
q