Our new Edelbrock #61189 Victor Jr. Cylinder Heads are designed for high output 650+ hp Chrysler 426-572 HEMI® engines. They feature fully CNC'd combustion chambers and CNC blended seats for optimal air flow performance. These cylinder heads also feature a revised exhaust valve angle to accommodate larger intake valves. They also feature brass tubes installed in exhaust pushrod holes to allow maximum clearance with minimal port intrusion.INSTALLATION NOTE: • Victor Jr. CNC cylinder heads #61189 are shipped with reamed and machined valve stem guides, as well as a valve job to match the included intake and exhaust valves (valves not installed). Customer must supply their own valve springs, retainers, valve stem seals and valve locks. • Recommended spark plugs are Champion RC12YC or equivalent 14mm x 3/4" reach with flat gasket seat.