skip white HEI timing issues

A photos and model# would help us help. I lost you on asking what initial timing the distributor has. You set that by rotating it and locking down the bolt. The distributor internals add centrifugal and vacuum advance to that.

You say the distributor has no pickup module inside it. How is that possible? Have you popped open the cover and looked?

If it is a small cap distributor, it would have a mag or Hall effect pick up in it and an external module. I'm guessing with no module, the MSD is doing the controlling. Try switching the wires as others have said.

You mentioned erratic spark or spark scatter. Was this a problem with the old distributor, also?