- Are the tachs set up for 6 cyl? It has switch on back and yes all set to 6
- Voltages dont seem out of line.
- Do you have any MSD boxes or the like.
- Points? I have points
- Have you contacted the tach manufacturers? One other havr no contact info we're bought through Amazon
- You might have black and green reversed ( don't think so but each wires things different) they each come with wiring diagram . But I tried both ways too
Tachs only need to see a on off signal from the coil to work.