What octane fuel are you running....

Most common cause is to much "Vacuum" advance at part throttle

You either have to limit the amount of advance caused be the vacuum advance or simply buy an adjustable one....Easiest way to tell is just to unplug it and retest....If you are not running a vacuum advance your mechanical may be comming in too soon which you will also have to limit or just back off by 2 degrees...

Depending on how efficient the cylinders are total timing at that compression should be no more than 34 all in by 3,000rpm...