Okay, here’s the problem. I have a rally tach in my 70 cuda. A MSD ready to run distributor is in the 440. The tach doesn’t register correctly and it has been rebuild during restoration in 2019. We have been on the phone constantly with MSD tech support but nothing we tried worked. We tried with a tach assist module with no luck. We tired it with an MSD ignition box but to no avail. We tried as many stabs as we could but the tach may read about two hundred rpms on startup but then drop to zero. I was curious if anyone else had a similar issue with this setup and what did you do to correct or resolve the problem? Any thought would be appreciated. I was going to try as many avenues as possible before removing the tach and having it examined. Thanks in advance.

I rebuilt my tach with the modern electronics about 14 years ago. 70Cuda. I also have an MSD 6al AND the tach module. It works.......but.....

If you are familiar with the normal operation of these vintage tachs, great. If not, be aware their response is SLUGGISH, and they are imprecise.

After all I did, I ended up mounting an Autometer tach right in front of the original.

Where can I get a tach rebuild kit for my ebody tach.