Installed new coil, now the tach acts funny

The two wires exiting the dist are low voltage AC. There is no + or - with AC, but sometimes you see the colours listed as + or - to ensure the correct wires get hooked up. Cannot see how either of these wires would trigger a tach. There were some tachs that triggered off the coil + terminal, but the vast majority trigger off the coil - terminal. SOME tachs will not trigger from elec ign [ Mopar, HEI, etc ] & might require one of the MSD adapters, 8910 or 8920 from memory. Above applies to inductive ign, not