Got it, Lowell was right, you have the four wire tach type. I am still confused as this setup won't have worked without a tach adapter with the MSD, though.

In your current setup, the black/white wire coming from the ignition key is directly wired to coil (+), so the tacho is not in line with the coil, which explains why it does not work.

You need to wire the tacho inbetween the resistor (block) and coil (+):

- The black/white wire and Pertronix red wire currently going to coil (+) must be connected to the resistor (the other side of the resistor is connected to green/white(yellow)).

- The black/yellow wire should be black/white and coming from the tacho, connect this wire to coil (+).

I've added a chart with the correct wiring below, hope this helps!

I think I understand now.... The green/white (yellow) wire and the black/white wire do a loop to/from the tach and need to be connected between/from the pertronix to the coil after the resistor... Makes sense... Thank you... I am not off work for a couple more days, but will let you know if it works.... Thanks

Thanks Adrian... That worked...

1 problem down 300,000 left.

Thanks again...

Chris