M6049-SCJA. Assembled Head for 429-460 Engines. They feature revised valve angles and locations to reduce cylinder wall shrouding and improve flow, along with redesigned combustion chambers to accommodate the more centrally located valves. These heads use the same valves, valve springs, retainers, and 7/16 in. stud-mounted roller rockers as the current Ford Racing 429 Cobra Jet heads, and the standard Cobra Jet intake and exhaust manifolds bolt right on. This new design offers a 25-50 HP increase over current Cobra Jet heads, depending upon displacement and camshaft. NOTE specs & photos can vary