I thunk dey wuz fer when yall remove the balance gears.
thinking cub 1650's didn't come with balance gears, mine didn't.
I would think a good pro balance job might help these big thumpers.
Not a fan of hanging a weight on the crank @ random.
Built a few balanced SBC's back in the day, utilizing a reputable balance shop in
Deetroit
they lived and ran good.