What's the easiest way to build high-quality rotating assemblies? Callies Compstar Speed Packs! Using components specially chosen for each application, Speed Packs are built around reliable 4340 forged steel Compstar crankshafts and connecting rods. Callies adds proven "brand name" components—forged aluminum performance pistons, ring sets, locks, and rod and main bearings—creating perfectly matched performance assemblies and a successful outcome for your project. Callies is serious about their quality and your success. Every Speed Pack crankshaft is dynamically balanced to components that are weight-matched to exact tolerances. You won't have to guess if you've paired the right components for power. Save by making the winning choice—Callies Compstar Speed Packs. bore 4.070 stroke 4.00. rod length 6.125. we have installed plenty of these assemblys and they are awsome. kit consists of crankshaft, rods, pistons, rod and main bearings and rings.