File this under "never seen that happen before". We made one good run, changed drivers and made second run. Motor started clean, ran good til third gear, started breaking up and then quit. I thought it was a plug or msd problem. Got home and found an unusual thing. The distributor had turned around 180 winding the plug wires around the cap. Pulled the dist and found this inside. I think a rotor screw came loose and turned the distributor into a blender. Never had to before but I guess I'll be using Loctite on the screws from now on.