Building a high-performance or high-horsepower engine requires components that can withstand immense stress and pressure. The main studs are the foundation of your engine’s rotating assembly, responsible for keeping the crankshaft securely in place. Using factory-grade or inferior hardware in a built motor is a recipe for disaster, making the choice of main studs one of the most critical decisions for engine builders seeking reliability and maximum strength.
Automotive Racing Products (ARP) is the industry leader in fastener technology, trusted by professional engine builders and racers worldwide. Their studs are engineered from superior materials and manufactured to exacting tolerances, providing a significant upgrade in clamping force and fatigue resistance over stock bolts. This roundup highlights the best ARP main stud kits for various applications, from classic small-block Chevys to modern LS engines and heavy-duty diesel powerplants, ensuring your engine’s bottom end stays together under extreme loads.
Our Recommended ARP Main Stud Kits
- ARP 2345608 Stud Kit for SB Chevy LS1
- ARP 2345501 Main Cap Stud Kit
- ARP Main Stud Kit, 12 Point Nuts for Dart LS Next Block
- ARP 134-5402 Main Stud Kit for Small Block Chevy
- ARP 247-5405 Main Stud Kit for Dodge Cummins 6.7L
- ARP 154-5401 Custom Age 625+ Head Stud Kit
- ARP 154-2501 Pro Series LS Head Stud Kit
- ARP 156-2501 Main Stud Kit for Small Block Chevy
ARP 2345608 Stud Kit for SB Chevy LS1
For builders working on a GM LS1 engine with a cast iron block, this vehicle-specific stud kit from ARP provides a direct-fit solution for enhanced bottom-end security. It is designed to replace the factory main cap bolts, offering a significant increase in clamping force to handle the stresses of high-performance driving and forced induction. The precise fit ensures a straightforward installation process for this popular engine platform.
This kit includes all the necessary studs and nuts to secure the main caps on your LS1 build. As with all ARP products, the fasteners are manufactured to strict quality standards, providing peace of mind that your engine’s foundation is robust. This is a fundamental upgrade for any LS1 project aiming for reliability beyond stock levels.
ARP 2345501 Main Cap Stud Kit
This main cap stud kit is engineered to meet the rigorous demands of professional engine builders. Manufactured from high-quality 8740 chrome moly steel, these studs offer a substantial strength advantage over standard Grade 8 hardware. With a impressive tensile strength rating of 200,000 PSI, they are built to prevent main cap walk and maintain alignment under extreme horsepower and RPM.
The kit is designed for applications where absolute maximum engine strength is non-negotiable. The material and construction provide superior fatigue resistance, ensuring long-term reliability in competitive racing environments. For any build where failure is not an option, this stud kit represents a top-tier choice for securing the crankshaft.
ARP Main Stud Kit, 12 Point Nuts for Dart LS Next Block
Specifically designed for the Dart LS Next aftermarket engine block, this kit ensures perfect compatibility and performance. It features 12-point nuts, which allow for easier tightening in confined spaces with a wrench or socket. This is particularly beneficial during the engine assembly process, saving time and reducing frustration.
This is a 4-bolt main stud kit, providing additional support and rigidity compared to 2-bolt configurations for serious high-horsepower LS-series builds. The chromoly steel construction with a black oxide finish offers excellent strength and corrosion resistance. If you are building an engine using a Dart LS Next block, this is the designated stud kit for the job.
ARP 134-5402 Main Stud Kit for Small Block Chevy
As a staple in the world of performance engines, the small block Chevy requires components that are both proven and powerful. This main stud kit from ARP is manufactured in the USA, guaranteeing a high level of quality control and material sourcing. It provides a direct upgrade for countless SBC applications, from street performance to all-out race engines.
The kit includes all the necessary studs and fasteners to securely anchor the main caps on your small block build. By upgrading to these studs, you significantly increase the clamping force on your main bearing caps, which is essential for maintaining crankshaft stability and preventing oil leaks. This kit is a fundamental building block for a strong and reliable Chevrolet V8.
ARP 247-5405 Main Stud Kit for Dodge Cummins 6.7L
Diesel engines, especially in high-torque applications like the Dodge Cummins 6.7L, generate tremendous cylinder pressures that can challenge stock fasteners. This ARP main stud kit is engineered specifically for these engines and includes components for vehicles equipped with a factory girdle. The girdle provides additional support, and this kit ensures it remains securely fastened.
Upgrading the main studs is a critical step for Cummins owners who are tuning or adding power. This kit helps prevent cap walk and maintains block integrity under the extreme loads produced by diesel combustion. For anyone building a durable and powerful 6.7L Cummins, this ARP stud kit is an essential component for engine longevity.
ARP 154-5401 Custom Age 625+ Head Stud Kit
While technically a head stud kit, the ARP 154-5401 deserves mention for its use of the exceptional Custom Age 625+ alloy. This material is renowned for its incredible tensile strength and resistance to heat and corrosion, making it ideal for the most extreme engine builds. It is often the go-to choice for engines with very high levels of boost from turbocharging or supercharging.
The properties of the 625+ alloy allow it to maintain clamp load under intense thermal cycling, where other materials might relax. This makes it a premium solution for preventing head gasket failure in ultimate performance applications. For builders who require the absolute best material science has to offer for cylinder head retention, this kit is a top contender.
ARP 154-2501 Pro Series LS Head Stud Kit
The Pro Series LS Head Stud Kit is designed for GM LS engines and represents a strong balance of performance and value. These studs are manufactured from high-quality materials to provide a significant upgrade over stock head bolts, offering improved clamping force for better head gasket sealing.
This is an excellent choice for LS engine builds that are running moderate boost levels or nitrous oxide. The kit ensures that the cylinder heads remain securely fastened to the block, maintaining combustion seal and preventing potential engine damage. For many LS performance projects, this Pro Series kit provides the necessary reliability and strength.
ARP 156-2501 Main Stud Kit for Small Block Chevy
This main stud kit is another robust option for the iconic small block Chevy platform. It is designed to provide a solid foundation for the crankshaft, enhancing the overall strength of the engine’s bottom end. The kit includes all the necessary studs for a standard small block Chevy main cap configuration.
By installing this kit, engine builders can achieve a more secure and stable crankshaft environment, which is vital for high-RPM operation and high-horsepower output. It is a straightforward upgrade that contributes significantly to the overall durability and integrity of the engine assembly, making it a smart choice for any performance-oriented SBC build.
Buying Guide: How to Choose the Best ARP Main Studs for Your Engine
When I’m building an engine for serious power, one of the first things I look at is the bottom end. The main studs are the foundation that holds your crankshaft in place and keeps your block from flexing under pressure. If you’re aiming for maximum engine strength, the stock bolts just aren’t going to cut it for a high-performance or forced-induction application. That’s where ARP main studs come in. They are the industry standard for a reason, but even within the ARP catalog, you have choices. Here’s what I focus on when picking a set.
First, you need to know your engine platform. ARP makes specific kits for everything from classic small-block Chevys to modern import engines. Getting the part number right is step one. Next, consider the material. ARP’s 8740 chrome molybdenum steel is their standard and is fantastic for most builds. It’s strong, reliable, and more affordable. But if you’re building an all-out race engine with insane cylinder pressure, like a big turbo or nitrous setup, you might want to step up to their 625+ stainless steel. This stuff is in another league in terms of tensile strength and fatigue resistance, but it comes with a higher price tag.
Another key point is the stud versus bolt debate. I almost always go with studs. Studs provide more consistent and accurate clamping force because they don’t twist during torquing like a bolt does. This gives you a more stable and secure main bore, which is critical for keeping your bearings happy at high RPM. The installation is a bit more involved, but the payoff in reliability is worth it.
Don’t forget about the fasteners that come with the kit. ARP’s Ultra-Torque lubricant is specifically designed for their fasteners to achieve an accurate clamp load. I never substitute it with generic engine oil or other lubes, as that can throw off your torque readings significantly. Also, check if your kit includes washers. Some do, some don’t, and they’re essential for preventing galling and ensuring a proper bearing surface.
Finally, think about your power goals and budget. For a street engine making a moderate 500-600 horsepower, a standard 8740 kit is a perfect, cost-effective choice. When you’re pushing four-digit horsepower numbers, that’s when the investment in a 625+ series makes sense. Matching the component to your actual needs ensures you get that maximum engine strength without overspending. It’s all about building a solid foundation you can trust.
FAQ
What makes ARP main studs better than stock main bolts?
Stock main bolts are typically made from lower-grade materials and are torque-to-yield, meaning they are stretched to their limit and designed to be used only once. ARP studs are made from high-strength alloys like 8740 chromoly or 625+ stainless steel. They can be reused multiple times and are designed to handle significantly higher clamp loads. This prevents main cap walk and block flex under high cylinder pressures, which is fundamental for achieving maximum engine strength in a performance build.
Do I need to align hone or line hone my block after installing ARP main studs?
In almost every case, yes, you should plan on an align hone. When you change the clamping force and method of the main caps, it can slightly distort the main bore where the crankshaft bearings sit. An align hone corrects this distortion, ensuring the bores are perfectly round and aligned. Skipping this step can lead to premature bearing failure and a crankshaft that doesn’t rotate freely. It’s an essential part of the professional installation process.
Can I use ARP main studs in a stock engine rebuild?
You absolutely can, but it might be overkill. If you’re just refreshing a stock engine that will never see a power adder or high RPM, the stock bolts are sufficient. However, if you think you might add power later or just want the peace of mind that comes with a stronger bottom end, installing ARP main studs during a rebuild is a great form of insurance. It’s one less thing to worry about if you ever decide to turn up the wick.
What is the difference between the ARP 2000 and ARP 625+ material?
ARP 2000 refers to their 8740 chromoly steel that’s heat-treated to achieve a 200,000 psi tensile strength. It’s the go-to for most high-performance builds. ARP 625+ is a different beast altogether; it’s a corrosion-resistant stainless steel alloy with a tensile strength of 260,000 psi or more. It’s significantly stronger and more resistant to fatigue, but it’s also more expensive and typically reserved for the most extreme applications like professional drag racing or high-horsepower turbo builds.
How important is the ARP thread lubricant, and can I use something else?
It is extremely important. The torque value you set on a fastener is just a means to achieve a specific clamp load. The lubricant used drastically affects the friction in the system. ARP’s Ultra-Torque lubricant is engineered to provide a consistent coefficient of friction. If you use engine oil or a different lubricant, the actual clamping force will be different for the same torque setting, potentially leading to an under-torqued or over-torqued stud. I never use anything but the lubricant ARP provides with the kit.