Cast from prime A356 T6 aluminum, these 'Z' heads from Ford Racing were designed using solid modeling technology. They feature high-flow ports and steel alloy intake and exhaust valve seats installed (they do require a competition valve job and bowl blending). The manganese-bronze valve guides are installed with a semi-finished I.D. and the combustion chambers are CNC-machined. Laser-cut guideplates are included, and they accept both tapered seat and gasket-style 14mm spark plugs.