ARP Diesel Custom Age 625+ Head Stud Kit 250-4205

The ARP Diesel Custom Age 625+ Head Stud Kit 250-4205 from XDP is the ideal upgrade for your competition or high-horsepower 2003-2007 Ford 6.0L Powerstroke. ARP is the industry leader when it comes to fasteners and offers heavy-duty head studs for a wide variety of popular diesel applications. Using head studs instead of standard head bolts provides your engine with the clamping force required to keep your cylinder heads from lifting due to higher combustion pressures. It’s a proven fact that OEM head bolts are the weak link in a diesel engine; especially when the engine has been heavily modified. That’s because most engines are typically assembled from the factory using weaker Torque-To-Yield (TTY) bolts and preloaded to yield and beyond (typically 100-110%). Any increases in combustion pressure can lead to problems like blown head gaskets or catastrophic engine failure. Furthermore, because TTY bolts are yielded by design, they should never be re-used.

The 247-4204 Head Studs utilize ARP’s Custom Age 625+ featuring a high-strength chromium-cobalt nickel alloy. This newly formulated super-alloy demonstrates superior fatigue cycle life, tensile strength and toughness, with complete resistance to atmospheric corrosion and oxidation. ARP is the first to develop manufacturing and testing processes for fasteners with Custom Age 625+. Tensile strength is rated at 260,000-280,000 psi and a yield strength of 235,000-255,000 psi. This results in a fastener that is stronger than Chrome Moly 8740 and ARP 2000 and is well suited for use in high-performance applications.

ARP head studs begin by being placed vertically into special racks and precisely heat-treated. This procedure ensures complete heat penetration and is far superior to those lower quality studs from other manufacturers who just place the pieces in a basket. Head studs then move to a centerless grinding process to ensure that they are perfectly concentric. As many as ten separate machining steps are required to achieve this level of accuracy. The thread rolling operation is also done after the heat-treatment, which gives them about 2000% (that’s 20 times) better fatigue strength than lesser studs that are threaded prior to heat-treat. It costs a lot more to do it this way, because it’s tough on tooling, but the results are worth the additional effort. Fasteners are then shot-peened to remove any surface irregularities and upgrade the overall external integrity. Finally, a metal finishing process is also performed in-house with a durable black oxide coating applied for improved corrosion resistance.

There is a good reason that virtually every top professional engine builder relies on ARP head studs for their all-out competition powerplants. Simply put, there’s not a better stud setup on the market today. This head stud kit is a direct-fit for the 6.0 Powerstroke engine found in Ford F-250/350/450/550 Super Duty pickups as well as the Ford Excursion. ARP also offers Inner Row Head Bolts as an add-on to complement these 6.0 ARP Head Studs (sold separately, see related items below).