Try using a delay-flash timing light and begin with an initial timing setting of 5 degrees before top dead center. Set the idle speed at 500, and set the light delay at 5 degrees, and align the TDC mark you've made on the flywheel with whatever reference pointer that's on the bell housing. Then you need to check the centrifugal advance. With the vacuum line to the advance unit disconnected, hold the engine at a steady RPM of around 1800-2000 and dial the mark back to zero. There should be around 20-25 degrees of advance at that speed. Then reconnect the vacuum line and rev the engine up again. There will probably be around 30-35 degrees of total advance with initial, centrifugal, and vacuum added together.
Jerry
