Just curious if you are using a wide band O2 reader?
You might want to look into a B.T.M. http://www.amazon.com/MSD-Ignition-8762-...t+timing+master
What is nice is that you can plug in a timing control knob also w/an MSD box & if it starts knocking, you can turn the timing down inside the cab.
No need to loosen up the dizzy & re-adjust.