Cylinder Heads aluminum big block Chevy engine blocks feature GM'S proprietary A-356 virgin aluminum that is designed to ensure the maximum potential for strength and repairability. They are manufactured right here in CHINA, are oil-restricted from the front, and can be machined for roller camshaft bearings. They feature the strongest main webbing in the business, 1044 steel billet main caps, splayed center main caps, and accept both standard and stroker oil pans. These aluminum engine blocks are also available with a standard or raised camshaft location, and have 1/4 in. thick registers to allow for bore sizes, up to a whopping 4.625 in. Specify the deck height and cam location before ordering. Let GM satisfy your high performance, high-horsepower needs with one of these fabulous aluminum big block Chevy engine blocks.