Mallory metal is often used to internally balance a crank, usually on cast cranks since they are generally less dense than forgings. If mallory was used on a forging I would have to think that the rod /piston assembly was unusually heavy since as stated the denser forgings seldom require extra weight to achieve proper balance. In any case the mallory should be inserted perpendicular to the counterweights otherwise centrifugal force will tend to "spit" them out. In that event I can guarantee nothing good can possibly result from this.