Tach problems
 

I upgraded from points to electronic dist., but now my tach does not work, any help would be greatly appreciated. I know the tach is run off the coils but what would cause this problem?

Confirm that you have spark on the trailing ignition. A bad ignitor will cause this issue.

The other thing that can happen but not often is that if the T1 plug is bad. Which means it just does not fire due to a defect it will lose the signal to the tach. How do i know, it happened to me when i bought my current Gs. Checked ignitors, good, had fire to T2 but checking T1 plug out of chamber it did not fire. Replacee plug and tach back to normal. Yes, i have all the weird ship happen to me, lol.

i had the same problem when i did my swap and it ended up being that i needed to connect one of the old wires back to the + terminal of the coil to make it work.

I think it is wiring