Balance plates. Who's right, Who's wrong

What we have is a 1 on 1 comparison between the SFI approved B&M 10236 plate for the back of a 360 crank and neutral balanced torque convertor. Up next is the Quick times QTMRM-531 for use with a neutral balanced flywheel used with a 360 crank. Balance results show one of these isn't quite like the other. By about 20 grams. Crank is balanced now for use with the automatic BUT I wanted to see how this stuff compared. Tested each plate attached to the crank individually and then mounted the 2 plates clocked 180* to see what that would net, if they were identical, they should have canceled each off-set to become "neutral". Not so, they were still out by about 20 grams to each other. FYI the QTM would need weight removed by 20 g's at the indicated jiffy mark.

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