1970 tach

[1970]

Hello everyone, I have a 70 runner with the factory tach/clock tic tic, I have a MSD ignition and at the time installed a MSD tach filter which lasted only a few minutes, then my tach quit, so now I replaced it with one of Herbs electronic tachs which was supposed to work with a MSD, well it jumps around so much I can't tell you what my RPM is, I pulled it back out and sent it back, they did "something" it worked but still was jumping, and now it's back to jumping so bad I can't even read it again (after a couple days) and Herbs will no longer acknowledge me.

 

[70chall440]

That sucks, sounds like there might be some electrical issues going on perhaps that is affecting the tach, have you tried an aftermarket tach?

 

[dla4567]

My did that with the Rev-N-ator box. Switched back to the chrome box and all is good. Don’t know why.

 

[BLK 68 R/T]

None of the tic-toc-tachs, factory or aftermarket are compatible with any aftermarket electronic ignition to my knowledge. Unless they have been upgraded with a different circuit board inside the tach. I have msd ignition on mine with a firecore dizzy. Repro tic-toc-tach and an msd tach adapter, this combo works on mine.

 

[Billccm]

Try an email to rt-eng.com. They might know if their circuit board solution will work.
A real long shot is to take a 10K resistor in series with the tach signal and see if it will settle.
I have some msd tach videos I could send you if interested.

 

[1970]

Well, see this; https://www.summitracing.com/parts/...-ntItWMikTJE6lnmrpei8yNlGIzMRdKUaAq6lEALw_wcB

I (as it says above) replaced the factory tach, there were two different tachs available, a voltage triggered (as original) and this one above. This one cost more than the original style, but the POS doesn't work

 

[BLK 68 R/T]

That’s the exact one I have, it is not compatible with electronic ignition unless you run a tach adapter.

 

[Beach Goat]

I have a tach adaptor to run my MSD 6al2 on my factory tic toc tach, and it works fine.