These unported versions of race-winning Edelbrock Victor Series CNC heads are designed specifically for the professional cylinder head porter and engine builder. Like all other Edelbrock Cylinder heads, Pro-Port cylinder heads are also cast in the USA at the state-of-the-art Edelbrock Foundry with extra-thick walls to allow for custom CNC porting. In most cases, seats and manganese-bronze valve guides are included, but not installed. Please note: These heads can not be used without professional head preparation. These heads can not be used without professional head preparation. With a true canted valve design (7.3° intake and 6.9° exhaust valve angles), these heads have maximum power potential. Extended intake flange and raised runners works with Yates-style manifolds.