Just bought a Duster that has a 340 and was trying to use a vacuum gauge to set timing. I am getting the most vacuum 18 inches with timing at 27 btc at idle total is about 52. When setting timing at 8 btc I am only getting around 10 inches.Don't know much about cam other than it is purple shaft specs unknown. The engine seems to Rev slow. What is best way to gethe timing set on this engine. At 27 it doesn't want to start. With timing set at 34 total the timing set at 8 btc and engine seems sluggish.