The Chevrolet aluminum big-block is back and better than ever. This block was first introduced in the 1969 Corvette and Camaro. It was one of the rarest production engines ever built. Now the improved version is available. This block is based on the original tooling. The new casting is made from 356-T6M aluminum alloy and has a 4.250" cast iron liner that can be bored to 4.300". The bottom end has also been improved with new 4-bolt splayed steel main caps, with dowel pins to locate and hold the caps in place. This block includes screw-in freeze plugs with o-ring seals, and a two-piece rear main oil seal. the new block has a provision for both dry sump or regular oil pump systems and mechanical fuel pump. All GM Performance Parts cylinder heads will fit this block and it weighs only 110 lbs. The maximum stroke is 4.375".