When building or repairing a high-performance or forced-induction engine, few components are as critical as the cylinder head studs. These fasteners are responsible for maintaining the crucial seal between the cylinder head and the engine block, combating immense combustion pressures and thermal cycles. Standard factory head bolts can stretch under extreme loads, leading to blown head gaskets and costly engine damage. For anyone pushing their engine’s limits, upgrading to a set of premium head studs is not an option—it’s an absolute necessity for reliability and peace of mind.
Automotive Racing Products (ARP) is the undisputed leader in this field, manufacturing high-strength fastener kits for virtually every application imaginable. Their studs are engineered from superior materials like chrome moly steel and are meticulously heat-treated to provide unparalleled clamping force and resistance to fatigue. This review will guide you through eight of the best ARP head stud kits available, highlighting their key features and intended applications to help you select the right set for your project, from diesel tow rigs to high-revving import tuners.
Our Recommended ARP Head Stud Kits
- ARP 247-4202 Stud Kit
- ARP 2304201 Head Stud for Chevy Duramax 6.6L
- ARP 2084305 High Performance 12-Point Cylinder Head Stud Kit
- ARP 208-4701 Head Stud Kit
- ARP 250-4203 Head Stud Kit
- ARP 260-4704 Head Stud Kit
- ARP 154-5001 Pro Series 8740 Chrome Moly Head Stud Kit
- ARP 154-2501 Pro Series 8740 Chrome Moly Head Stud Kit
ARP 247-4202 Stud Kit
This ARP stud kit is designed for builders who understand that proper installation is key to achieving maximum performance. The kit includes specific instructions to lubricate both sides of the washers with ARP’s proprietary Ultra-Torque Fastener Assembly Lubricant before placing them over the studs onto the cylinder head spot faces. This meticulous process ensures an accurate and consistent clamp load across all cylinders, which is fundamental for head gasket sealing and engine longevity.
By following the recommended procedure, you minimize friction during torquing, allowing the stud to stretch correctly and develop its full rated clamping force. This attention to detail is what separates a professional-grade engine build from an amateur one. This kit is an excellent choice for those who refuse to cut corners and demand reliability from their engine components.
ARP 2304201 Head Stud for Chevy Duramax 6.6L
For owners of the Chevy Duramax 6.6L diesel engine, this ARP head stud kit is a vital upgrade, especially for trucks that are tuned, used for heavy towing, or see high boost pressures. The immense cylinder pressures generated in a diesel engine can easily overwhelm factory head bolts, making this kit a popular solution for preventing head gasket failure. The black oxide finish provides a durable layer of protection against corrosion, ensuring the studs remain in optimal condition.
Proudly made in the United States, this kit reflects ARP’s commitment to quality and manufacturing excellence. Each stud is engineered to provide a superior and consistent clamp load, keeping the cylinder head securely fastened to the block under the most demanding conditions. This is a vehicle-specific solution that delivers the strength and reliability that Duramax owners depend on.
ARP 2084305 High Performance 12-Point Cylinder Head Stud Kit
The ARP 2084305 kit features a 12-point head design, which is a favorite among professional engine builders and serious enthusiasts. The 12-point configuration allows for easier tightening in confined engine bays, as it offers more engagement points for a wrench or socket. This can be a significant advantage when working in tight spaces where swing room is limited, making the installation process more efficient and less frustrating.
Like many of ARP’s premium products, this kit is manufactured in the USA, guaranteeing a high standard of quality control and material integrity. The package is compact yet substantial, reflecting the dense, high-strength nature of the components inside. This kit is built for high-performance applications where every detail, from the material to the fastener design, contributes to overall engine robustness.
ARP 208-4701 Head Stud Kit
ARP positions this head stud kit as the go-to choice for those who simply want the best. The branding emphasizes strength and reliability with straightforward messaging like “When you want strong, go with ARP.” This kit is engineered for a broad range of applications, making it a versatile option for various engine projects that require a significant upgrade in clamping force over stock fasteners.
It is marketed as a precision product suitable for street, offroad, and Powersports applications, indicating its versatility across different types of vehicles and engines. Whether you’re building a high-horsepower street machine, a rugged off-road truck, or a high-revving motorcycle engine, this kit is designed to meet the challenge. It represents the core ARP philosophy of providing superior strength for demanding environments.
ARP 250-4203 Head Stud Kit
This is a vehicle-specific solution engineered for the Ford 6.4L Powerstroke diesel engine. The 6.4L Powerstroke is known for its performance potential, but stock head bolts can be a weak point under increased power. This ARP kit is the definitive answer for owners looking to build a reliable, high-power diesel engine capable of handling custom tuning and additional boost without the risk of head gasket issues.
The part number 250-4203 is specifically designed to fit the 6.4L Powerstroke, ensuring a perfect match and a hassle-free installation process. By upgrading to these studs, you are directly addressing a known limitation of the platform, thereby increasing the engine’s durability and allowing it to safely support significant performance modifications. This is an essential upgrade for any serious 6.4L Powerstroke build.
ARP 260-4704 Head Stud Kit
Targeted at the massive Subaru EJ20 and EJ25 engine community, this head stud kit is a cornerstone of Subaru performance builds. The turbocharged Subaru boxer engine is famous for its power potential but is also known for its susceptibility to head gasket failure under stress. This kit, made from CA625+ material, provides the necessary strength to keep the cylinder heads sealed during high-boost applications.
The compact package dimensions and weight reflect a complete kit for the horizontally-opposed engine configuration. For anyone building a high-performance Subaru WRX or STI, this is one of the first and most critical upgrades to consider. It provides the foundational strength needed to reliably support power increases from turbo upgrades, engine management tuning, and other performance modifications.
ARP 154-5001 Pro Series 8740 Chrome Moly Head Stud Kit
As part of the Pro Series, this kit is constructed from 8740 chrome moly steel, a material renowned for its excellent strength-to-weight ratio and high fatigue resistance. This type of steel is heat-treated to achieve an optimal balance of strength and toughness, making it ideal for the repeated stress cycles experienced in a high-performance engine. The Pro Series is often the choice for professional race teams and builders who require proven, competition-grade components.
The use of 8740 chrome moly allows these studs to maintain their clamping force under extreme temperatures and loads, preventing the head gasket from losing seal. This kit is suited for a wide range of engine types where maximum reliability and performance are the primary goals. It represents a top-tier option within the ARP lineup for serious engine builds.
ARP 154-2501 Pro Series 8740 Chrome Moly Head Stud Kit
This is another offering from the respected ARP Pro Series, also utilizing 8740 chrome moly steel. The different part number indicates it is designed for a specific engine application not covered by the 154-5001 kit. The consistent use of premium materials across the Pro Series ensures that regardless of the engine platform, you are receiving the same high level of quality and performance.
These studs are engineered to provide a permanent solution to head gasket sealing issues in modified engines. They are significantly stronger than OEM bolts, which means they do not stretch under load, maintaining a consistent clamp on the head gasket. For any engine build where failure is not an option, selecting a Pro Series kit like this one provides the confidence needed to push the engine to its limits.
Buying Guide: How to Choose the Right ARP Head Studs
When you are building an engine for more power, the factory head bolts often become the weakest link. That is where upgrading to a set of ARP head studs comes in. I have used them in countless builds, from mild street engines to all-out race motors, and the difference in clamping force and reliability is undeniable. But with several product lines available, choosing the right set for your project is critical. Let me walk you through what I look for.
First, you need to understand the material. ARP’s most common studs are made from 8740 chrome-molybdenum steel. This is an excellent, proven material for the vast majority of high-performance and street/strip applications. It offers a significant strength increase over stock bolts and is more than capable for builds making up to 700-800 horsepower. For extreme applications, like a turbocharged monster or a high-revving nitrous engine, you should step up to ARP’s 625+ “Super Alloy” or 2000 series stainless studs. These alloys maintain their strength under immense heat and pressure, providing an extra layer of security when your engine is under maximum stress.
Next, consider the design. Studs are generally superior to bolts because they don’t twist during torquing, allowing for a more accurate and consistent clamp load across the cylinder head. ARP also offers different thread pitches. A fine thread, like the ones often found in their “L19” or “Custom Age 625+” products, allows for more precise torque adjustment and can achieve higher clamp loads. For most common V8 engines, a standard coarse thread in their 8740 material is perfectly sufficient.
Finally, do not overlook the installation hardware and preparation. A quality set of ARP head studs typically comes with everything you need, including high-quality nuts and washers. I always make sure to use the specific lubricant ARP provides, as using engine oil or other lubricants can drastically alter the torque reading and lead to under or over-torquing. Proper thread cleaning in the block is also a non-negotiable step I never skip; any debris left in the threads can cause inaccurate torque readings and compromise the entire installation. Taking your time here pays off with a sealed engine that can handle the power you are throwing at it.
FAQ
What is the main advantage of using ARP head studs over factory torque-to-yield bolts?
The biggest advantage is reusability and consistent clamping force. Factory torque-to-yield (TTY) bolts are designed to be stretched to their yield point during installation and are meant to be used only once. This is fine for a stock engine, but if you are doing any work that requires removing the cylinder head, you must replace them. ARP studs, on the other hand, are designed to be used multiple times. They provide a much more consistent and stronger clamp, which is essential for preventing head gasket failure under high cylinder pressures from boost, nitrous, or high compression.
Do I need to have my block’s threads tapped or chased for ARP studs?
In almost every case, yes, you absolutely should. This is one of the most important steps I do before any build. The threads in your engine block can accumulate debris, paint, sealant, and minor corrosion over time. Simply screwing in a new stud won’t clean them properly. You need to use the correct size bottoming tap to clean the threads all the way to the bottom of the hole. This ensures the stud screws in smoothly and seats fully, which is critical for achieving an accurate torque reading and even clamping force across the head.
Can I use engine oil instead of the ARP thread lubricant?
I strongly advise against it. The specialized lubricant that comes with your ARP head studs is formulated to have a specific, consistent coefficient of friction. When you apply a torque value to a fastener, a significant portion of that force is overcoming friction. If you use engine oil, which has a different friction rating, the actual clamping force applied to the stud will be different than what ARP engineers calculated for their torque specifications. Using the wrong lube can lead to under-torquing (and a blown head gasket) or over-torquing (and a stretched or broken stud). Always use the supplied lube.
What is the difference between the standard ARP 8740 studs and the more expensive 625+ studs?
The difference comes down to material and ultimate tensile strength. The standard 8740 chrome-moly studs are incredibly strong and perfect for most high-performance applications. The 625+ “Super Alloy” studs are made from a nickel-chromium alloy that retains its strength at much higher temperatures. If you are running a turbocharged, supercharged, or nitrous engine that sees extreme heat and cylinder pressure, the 625+ studs offer a greater safety margin. For a naturally aspirated street engine, the 8740 studs are typically more than enough.
How important is the torque sequence and the recommended three-step torque process?
It is extremely important. The cylinder head and block can warp if you just tighten the fasteners down in a random order or all at once. The sequence, usually starting from the center and working outwards in a spiral pattern, ensures the head is pulled down evenly onto the gasket. The multi-step torque process (e.g., 50 ft-lbs, then 75 ft-lbs, then final torque) gradually compresses the head gasket and allows everything to settle. Skipping steps or the sequence is a surefire way to end up with a leaky head gasket, even with the best ARP head studs installed.