AFR Direct Master Warehouse Distributor - All AFR Products Available. AFR 457cc BBC 18° Magnum Cylinder Heads. 950, IN STOCK on our shelves. AFRs new 457cc 18° Big Block Chevy heads are our best performing highest flowing head in our BB Chevy lineup. They come standard with stainless steel 2.400 intake valves and 1.800 exhaust valves. The intake port is raised. 500 with the valves rolled to 18° resulting in unparalleled under the curve flow numbers..... Dont be fooled by just peak flow numbers. The combustion chamber comes in at 90cc. This head is ideal for 540CI or larger race engines. This head requires specific pistons, valves covers, shaft mount…