The Victor DR23 Cylinder Head #614468 for Chevy Big-Block engines is Edelbrock’s third generation of the Victor Chevy BB head. This bare cylinder head is fully CNC ported with a race-oriented design for those who demand a high-performance head with durability that they can rely on. The DR23 retains the use of conventional intake manifolds, the most recent of which are the Super Victor II #2896 for 9.8-inch deck Chevy BB engines with a standard thick flange, and the Super Victor II #2897 for 10.2-inch tall-deck engines. The evolved head architecture of the DR23 takes advantage of the improved capability of the new manifolds. A rolled deck from the second-gen design produces a 23-degree valve angle. Other improvements include revised intake and exhaust valve locations, improved spark plug placement, and a new water jacket that is more head porter friendly than previous heads. The DR23 is a CNC-ported finished cylinder head. For those who wish to do their own port work, Edelbrock offers the BV3 Head #614669. Both the DR23 and BV3 are manufactured with special small-run production methods for the highest quality results. This includes Hot Isostatic Press processing in which raw aluminum castings are heated to 900 degrees Fahrenheit in a pressurized chamber with up to 30,000 PSI. This eliminates imperfections by removing any trapped gases or internal porosity. The result is an incredibly strong, dense sand casting that has three times the fatigue life and nearly the consistency of billet aluminum. HIP-processed heads have less chance of failure due to fatigue and also provide a smoother machined surface when port and chamber work is applied. The DR23 uses a stock Chevy head bolt pattern but requires a shaft rocker system and is designed to be used with Edelbrock 7-bolt valve covers sold separately under part number #4259. Valve sizing is 2.40-inch on the intake and 1.88-inch on the exhaust with 119cc chamber volume. Port volumes are 377cc intake and 128cc exhaust.