Originally Posted by
tyor
try to retard the ignition, it will help.
Thanks tyor,
Did the following and it seemed to help reduce vibration and the shakes at idle:
Smaller diameter prop. Reduced size from 20-8 to 19-8.
Retarded ignition a little which lowered top end by 200 RPM.
Used 93 octane gasoline.
Still have sufficient power, I think, for 18 pound Phoenix Stinson Reliant. With 19-8 prop now doing 6850 RPM.