Using 1.6 rockers is problematic due to the pushrod angle and weight of valve train with fast rate cams when revving over 6000. With this much lift they would need a solid lifter, or factory magnum hydraulic rollers to use 1.6 rockers. Also use beehive springs to lighten valvetrain if using 1.6’s. 1.5’s just seem to work easier For most street engines.
