HAISLEY MACHINE HAISLEY-MAINS MAIN STUD KIT 12MM L-19 EXTRA LONG FOR 5.9L & 6.7L CUMMINS

Product Description

When building a high-horsepower Cummins engine, the factory main fasteners quickly become a weak link. The HAISLEY MACHINE HAISLEY-MAINS MAIN STUD KIT 12MM L-19 EXTRA LONG was engineered specifically for serious diesel performance builds that demand superior block stability and clamping force. Built using premium L-19 high-strength material and manufactured for Haisley Machine by ARP, this extra-long main stud kit is designed to securely tie the main caps to the block when running a modified girdle system. These heavy-duty studs provide a massive improvement in block integrity, helping prevent main cap walk, crankshaft instability, and bottom-end failure in high horsepower Cummins engines. Each stud features a glass bead finish and hex broach for precise installation, while the included 12-point black oxide nuts and hardened washers deliver consistent clamping force under extreme cylinder pressures. Whether you're building a competition puller, drag truck, or high-boost street build, the HAISLEY MACHINE L-19 extra long main stud kit provides the strength required to support serious power levels. Haisley Machine Cummins main studs, 12mm Cummins main stud kit, Cummins girdle main studs, L19 Cummins studs, ARP Cummins main studs, high horsepower Cummins block reinforcement, Cummins performance engine hardware, diesel competition engine studs, 5.9 Cummins racing hardware, 6.7 Cummins performance build hardware

Kit Includes

• 14 × 12mm L-19 Extra Long Main Studs
• 14 × 12-Point Black Oxide Nuts
• 14 × Hardened Alloy Washers
• Installation Instructions

Performance Benefits

• L-19 premium material rated at approximately 240 ksi tensile strength
• Designed to tie main caps to engine block with girdle setups
• Improves bottom-end rigidity for high horsepower builds
• Manufactured for Haisley Machine by ARP for precision quality
• Glass bead finished studs with hex broach for easy installation

Fitment

• 1997.5–2007 Dodge Ram 2500 / 3500 – 5.9L Cummins
• 2007.5–2018 Dodge / Ram 2500 / 3500 – 6.7L Cummins
• Compatible with Encore or newer B-Series Cummins blocks
• Designed for engines using a modified main girdle system

As horsepower levels in modern Cummins engines continue to increase, longer main studs allow builders to connect a block girdle directly to the main caps, dramatically improving engine block strength and reliability under extreme load. 

FAQ

What makes L-19 main studs stronger than standard studs?

L-19 alloy steel provides significantly higher tensile strength than common fastener materials like ARP2000, allowing the studs to maintain clamping force under extreme cylinder pressures in high horsepower diesel engines.

Why are these studs extra long?

The extra length allows the studs to pass through a block girdle and securely clamp the main caps and block together. This dramatically increases bottom-end rigidity in high-power Cummins builds.

Is this kit required for high horsepower Cummins builds?

While not mandatory for stock engines, performance builds making large amounts of boost and cylinder pressure benefit greatly from upgraded main studs to prevent main cap movement and block stress.

Are these studs manufactured by ARP?

Yes. Haisley Machine partners with ARP to manufacture these studs to their specifications, ensuring premium metallurgy and precise machining.

Can these studs be used without a girdle?

They can be installed without a girdle, but they are specifically designed to provide the correct length for girdle applications.

Specifications for HAISLEY MACHINE HAISLEY-MAINS