ARP 251-6422 Cylinder Head Fasteners

ARP 251-6422 cylinder head fasteners are precision-engineered to deliver exceptional clamping force and reliability for demanding engine applications. These fasteners are manufactured using ARP's proven aerospace-quality materials and manufacturing processes, ensuring consistent performance under extreme cylinder pressures and temperatures.

Key Features:

• Precision CNC-machined to exacting tolerances for perfect fitment
• Heat-treated using specialized vertical racks to ensure complete 360-degree penetration
• Threads rolled after heat treatment to provide superior fatigue strength
• Forged in-house at ARP using premium quality alloy materials
• Application-specific design optimized for cylinder head retention
• Includes premium hardened washers where applicable

Material Excellence:

ARP fasteners undergo rigorous quality control throughout the manufacturing process. Each fastener is heat-treated to precise specifications and undergoes post-heat-treat thread rolling, which work-hardens the material and creates a surface compressive stress that dramatically increases fatigue life. The result is a fastener that can withstand repeated thermal cycles and extreme cylinder pressures without stretching or failing.

Installation:

ARP fasteners require proper installation procedures including use of ARP Ultra-Torque assembly lubricant and following manufacturer-specified torque sequences and values. Proper installation ensures optimal clamping force and gasket sealing while preventing thread galling and ensuring accurate torque readings.