The DR17 is the next evolution in Edelbrock conventional style big-block Chevy cylinder heads geared for the sportsman racer. They are designed to deliver consistent and reliable performance through the whole race season. These cylinder heads are based off our popular Victor 24° Gen II Pro-Port Raw design, but features a revised valve angle and location for improved flow and performance. The casting is Hot Isostatic Pressing (HIP) processed for superior strength, durability and exceptional finish quality. Requires the use of shaft rocker system. Tall-deck applications will require the use of spacers. INSTALLATION NOTES: Deck thickness: 9/16", rocker stud diameter: 7/16", pushrod diameter: 3/8" (width of slot in guide plate). Bare heads will have valve guides and seats installed, but will require final sizing and a valve job to match the valves you will be using.