Hello. I have a '73 Fastback with the factory tach and gauge setup. I want to add a MSD box to the car but want to keep the factory tach. Is it possible to use the factory tach with a MSD? It looks like the tach gets it signal from the positive side of the coil instead of the the negative side like a traditional tach. Any help would be appreciated.

 

you do not want to run a factory tach with a MSD box, it will fry the tach

 

Maybe the MSD tach adapter is what you need...

 

thanks... that's what i needed to know.....i was hoping there was a way to make it work, but i guess i'll try to mount an autometer tach in the dash instead. thanks again.

 

^^^there should be a MSD tach adapter so you dont need to buy a new tach to get it to work with ur MSD.

Like this. (was just a quick search)
http://www.sdpc2000.com/catalog/1572...ch-Adapter.htm

 

NO This is incorrect. I have a 73 with an MSD it will not fry the tach. The voltages are different so the tack will not register correctly. I added a tach adapter and mine works fine and registers correctly.