The Chevrolet Performance Rocket Engine Blocks is a cast iron block that is precision CNC machined and does not require additional blueprinting to correct production tolerances. All block dimensions are machined to +/- .001". The blocks extra-thick siamesed cylinder walls provide a minimum .275" wall thickness with a 4.125" bore. The cylinders can be bored to a maximum of 4.155" diameter.

The outer water jacket walls are scalloped to enhance coolant flow around the siamesed cylinders. This block is available with deck height 9.325". The reinforced deck has a minimum .625" deck thickness, regardless of the deck height specified. The head blot holes are blind-tapped and the head bolt bosses are freestanding to minimize cylinder bore distortion!