SBF 4340 Forged Crank 3.400 Stroke Int Balance

The LUNATI SBF 4340 Forged Crank with 3.400 Stroke and Internal Balance is a precision-engineered crankshaft built for Small Block Ford engines demanding maximum reliability and performance. Forged from 4340 steel, this crankshaft delivers the structural integrity required for high-output applications, whether in street performance, racing, or heavy-duty service. The internally balanced design eliminates the need for external counterweights, streamlining installation and reducing complexity in engine builds.

The 3.400-inch stroke specification is critical for displacement and torque characteristics in Small Block Ford platforms. Internal balancing distributes the rotating mass evenly within the crankshaft itself, resulting in smoother operation, reduced vibration, and extended bearing life under sustained load. The one-piece main seal design simplifies the rear seal application and reduces potential leak paths—a practical advantage during assembly and long-term service. At 53 pounds, this crankshaft carries the weight typical of forged steel construction, reflecting the material's superior fatigue resistance compared to cast alternatives.

This component serves engine builders and performance enthusiasts constructing or rebuilding Small Block Ford engines for street applications, drag racing, or marine duty. The forged 4340 steel construction handles increased boost pressure, nitrous oxide systems, and high rpm operation more reliably than cast counterparts. Whether for a complete engine overhaul, performance upgrade, or replacement in a damaged short-block, the LUNATI crankshaft provides the durability and precision required for serious builds.

Small Block Ford crankshafts are foundational components in one of the most popular American engine platforms. The 3.400-inch stroke sits in the mid-range for SBF applications, balancing off-the-shelf availability of matching components with solid displacement and torque production. Internal balancing is the preferred specification for street and racing builds where reducing vibration and improving drivability matter significantly.