What spark plugs are you running, brand and part #? I had a low compression(8.5 to 1 actaul) I/O drive boat motor that would ping using a Champion J12Y spark plug set but wouldn't ping using the next lower heat range, J11Y I would try the next colder heat range spark plugs The last iron headed 440 motor I tuned until it ping didn't like any total timing above 36 degrees on Oreogon non ethanol 91 octane pump swill I would put the total timing at 34 degrees revved up and readjust the intial to get between 14 and 18 BTDC I like and use really weak advance springs in my distributors so the total timing is all in by 2000 RPM My converters are a lot looser than that at WOT, they will flash to 4400 RPM or higher There very similar driving on the street to a stock Mopar 11 inch converter at light part throttle pressures below 3000 RPM also