I'm trying to adjust the timing on my 69 351w 4v. Its pretty much stock except for a duraspark electronic ignition. What should I be setting the initial timing at? My shop manual says 6 degrees. When I set it at this and shut the car off, it "runs on". I set it back to the inital setting (0) and it still runs on. I plugged the vacuum advance before doing any of this. The 6 degree setting is 6 degrees clockwise when lookin at the front of the engine. What am I doing wrong??