4.040" Bore Forged Piston Set

The DSS Racing 3971-4040 is a set of high-performance forged pistons engineered for Small Block Ford 400M engines. These pistons are crafted from either premium 4032 low expansion alloy (FX-1 series) or premium 2618 alloy (FX-2 and FX-3 series), offering durability and reliability for demanding applications. The FX-3 series further enhances performance with features like horizontal gas ports for improved ring seal and Extreme Duty XR wrist pins. Designed with a 4.040-inch bore, these pistons feature a -13cc dish top, suitable for use with 351 Cleveland and Boss open & closed chamber cylinder heads. Key specifications include a 1.710-inch compression height, a 0.975-inch pin diameter, and ring groove dimensions of 1.2/1.2/3MM. The pistons are designed for a 4.000-inch crankshaft stroke and a 6.580-inch connecting rod length, with a TDC assembly height of 10.290 inches for a zero deck height. Available options allow for customization, including the choice of piston series (FX-1, FX-2, FX-3) and whether to include a DSS Racing piston ring kit. The FX-3 series offers advanced features such as patented 'X Groove' skirts for superior cylinder and ring life, additional CNC milling for weight reduction, and enhanced oil control features like low volume contact reduction grooves and oil ring groove relief reservoirs. All DSS Racing pistons are forged and machined in the USA.