For serious engine builders working on competition big-block setups, this Edelbrock Victor Jr. cylinder head is the real deal. The 24-degree rectangular port design with 300cc ports delivers insane airflow and power potential for engines up to 510 cubic inches with 4.310 or larger bore. What's impressive is the extra thick deck and additional material in the spring pockets - this is a heavy-duty casting built to handle high-lift cams and serious spring combinations without flexing or failing. The exhaust ports are raised .534 inches over stock, which dramatically improves exhaust flow and power output. Edelbrock gives you spring package options too - choose hydraulic for flat tappet or hydraulic roller cams up to .700 lift, or go with the mechanical roller spec that includes Manley dual-spring valve springs and titanium retainers good for up to .880 lift. At 25.8x11.4x8.5 inches, these are substantial pieces of engineering. If you're building a drag racing engine, street monster, or any high-performance application where every horsepower counts, these Victor Jr. heads deliver that competitive edge Edelbrock is famous for.