The ARP 250-5801 is a high-strength main stud kit engineered for 1994–2003 7.3 Powerstroke diesel engines. Manufactured from ARP’s proprietary ARP 2000 alloy steel rated at a minimum tensile strength of 220,000 PSI, this kit replaces the factory main bearing cap bolts to lock the crankshaft down securely in the bottom end. ARP heat-treats each stud prior to thread rolling and centerless grinding, packaging the kit complete with precision-machined parallel-ground flat washers, 12-point nuts, and ARP Ultra-Torque fastener assembly lubricant.

Main cap fretting, bearing distortion, main cap walk, and catastrophic crank failure under extreme torque and high horsepower loads are what this stud kit eliminates. The factory main cap bolts flex and stretch when subjected to the elevated cylinder pressures and heavy rotational stresses generated by competition tuning, large hybrid injectors, and high-boost turbo setups. Upgrading to ARP 2000 main studs drastically reduces bottom-end deflection, eliminates crank walk, and maintains precise crankshaft bearing clearances during high-RPM and heavy towing abuse. It is the engine main stud, washer, and 12-point nut hardware kit only; main bearings and crankshaft are sold separately.

It fits all 1994–2003 7.3 Powerstroke Ford Super Duty trucks, OBS F-Series, Excursions, and E-Series vans equipped with factory main bearing caps.

Fitment

• 1994–1997 Ford F-250 / F-350 OBS 7.3L Powerstroke
• 1999–2003 Ford F-250 Super Duty 7.3L Powerstroke
• 1999–2003 Ford F-350 Super Duty 7.3L Powerstroke
• 1999–2003 Ford F-450 / F-550 Super Duty 7.3L Powerstroke
• 2000–2003 Ford Excursion 7.3L Powerstroke
• 1994–2003 Ford E-Series Vans 7.3L Powerstroke
• Navistar T444E diesel engines
• Manufactured from heat-treated ARP 2000 alloy rated at 220,000 PSI
• Precision rolled threads with centerless ground finish
• Includes hardened parallel-ground washers and 12-point nuts
• Supplied with ARP Ultra-Torque fastener lubricant
• Complete bottom-end main stud hardware kit only

Thoroughly chase and clean all female main bolt holes in the engine block deck using a thread chaser or bottoming tap, blowing out every hole completely dry of residual oil, solvent, or debris with compressed air. Thread the studs into the block hand-tight only using an Allen key in the top hex socket—never torque studs into the engine block. Because studs create a significantly higher and more uniform clamping load than factory bolts, a professional line bore/line hone check of the main journal bores is strongly recommended prior to final engine assembly. Coat the upper exposed stud threads, washer faces, and nut mating surfaces liberally with the supplied ARP Ultra-Torque assembly lubricant, then torque the 12-point nuts in the factory inside-out pattern across three equal, progressive steps up to ARP's final specified torque value.