Engine - Cylinder Heads - Raised Runner Aluminum Bow Tie Head

From GM Performance - Technical Notes: The raised runner head is sold without valve guides and seats. The raised port design requires aftermarket valve which are .100 inch longer than stock. Production valves can be used by remachining spring pockets. Pushrod clearance holes are elected to allow widening of the intake ports. Pushrod guideplates P/N 14011051 are required with raised runner heads. Raised runner intake manifold P/N 10051103 is recommended for all single four-barrel applications.