1 This project's foundation is a seasoned Gen III Hemi block that has been squared, decked, and align-honed, etc. at Muscle Motors. These iron 5.7 blocks use the same 4.46-inch bore spacing as the old LA-series of small-blocks. Muscle Motors bored the block to 0.030-inch over (3.947 inches), and you can see there's still plenty of meat left between the cylinders. The sturdy, deep-skirt construction of these Gen III blocks puts their weight somewhere between that of the LA small-block and RB big-block. By the way, if contemplating your own Gen III Hemi buildup, Muscle Motors recommends starting with a 2008-or-older block, as newer blocks had some changes (required for variable cam timing, etc.) that would complicate the use of aftermarket parts.