Fully assembled, the heads weigh 38-pounds each, a full 26-pounds less than iron Hemi heads. This 52-pound savings plus the 70-pound lighter wedge block drop the total weight of this 520-inch conversion motor to 607 pounds versus 730 of an iron 426. To accommodate the shape of the wedge block's lifter valley and get needed exhaust pushrod clearance, SVE moves the exhaust rocker arms 1/2-inch closer to the center of the block via specific extruded aluminum rocker shaft stands. These heads also require special cast stainless steel roller rocker arms that are1/2-inch longer than stock 426 parts. The conversion kit also comes with cast stainless steel roller intake rocker arms.