The Edelbrock 770769 Small Block Ford SC1 Pro-Port Cylinder head is designed specifically for the professional cylinder head porter and engine builder. Like the other Edelbrock Cylinder head, The Pro-Port cylinder head is 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: This head can not be used without professional head preparation.