Have a Weber 50220 11 inch aluminum BBC (?) flywheel. Would appreciate learning whether this was an externally balanced flywheel. Might be since it has 5 br*** 1/2 inch plugs on outer edge of wheel, outside of the riveted steel insert. Comments appreciated. Would be for sale also. Duane
Certainly sounds like an externally balanced flywheel. Do you have a local machine shop who could spin the wheel on their balancing machine and give you a reading?
You may be able to spin it on a tire balancing machine, center it with the tapered cones. It should tell you how much it is out of balance.