Fast-Burn Cylinder Head Assembly

The Vortec cylinder head assembly is a high-performance cast iron component offering significant power gains for small-block Chevrolet engines. Known for its fast-burn combustion chamber and high-velocity ports, it provides a substantial horsepower increase over earlier cast iron heads. This assembly comes completely built with valves, springs, retainers, and 3/8" rocker studs, and requires the use of self-aligning rocker arms. The Vortec head utilizes 1.94" intake valves and 1.50" exhaust valves, complementing its port design. It can be mildly ported for further performance enhancements and milled up to .040" to increase compression ratio. The head's improved manifold mounting flange and gasket design, along with raised intake ports, necessitate the use of a Vortec-style intake manifold; modification to accept early design manifolds is not recommended. Technical specifications include a maximum camshaft lift of .475" without modification to the valve guide bosses; exceeding this lift requires re-machining to prevent crushing valve stem seals. The valve seats can be machined to accommodate 2.02" intake and 1.60" exhaust valves, and the rocker arm studs can be pinned or drilled and tapped for 3/8" hardware. The valve spring seat diameter is 1.48". Casting part numbers include 10239906 or 12558062. This assembly fits all small-block Chevrolet engines produced from 1955 to the present, with the exclusion of LT1/LT4 reverse coolant flow engines and current LS1 style engines.