the 400 crank does not have the clearence that a 350 has and cam lifts over .370 (.50@the valve) might cause one or more of the lobes to touch the edge of your rods depending on lobe seperation. when listening with a stethascope the noise is strange because it doesn't seem to match the harmonics of the crank or the cam. might i add been there done that . Launiti recomends that you dont exceed .512 at 102 deg. lobe seperation unless you use a smaller base circle cam with rollers.