ARP 12-Point Engine Head Bolt Set 0.4375-16 UNC Premium Alloy Steel

Description

Product Overview

When a race‑engine builder talks about reliability, the ARP 12‑point engine head bolt set is often the first name mentioned. Engineered from premium 8740 alloy steel, each stud is heat‑treated to achieve a minimum shear strength of 220,000 psi—far exceeding standard Grade 8 hardware. The 0.4375‑16 UNC thread size, right‑hand 12‑point head, and Class 3A tolerance ensure a perfect fit for a wide range of high‑performance engines. The kit includes parallel‑ground washers and compact 12‑point nuts, all centerless‑ground for concentricity, delivering a bolt‑on experience that eliminates misalignment and maximises clamping force.

Usage

Designed for serious enthusiasts and professional engine builders, this bolt set excels in competition‑level builds, street‑performance upgrades, and heavy‑duty applications where durability is non‑negotiable. Whether you are assembling a forged‑aluminum cylinder head, rebuilding a high‑compression V8, or reinforcing a turbocharged platform, the ARP studs provide the consistent torque retention needed for peak power delivery. Their 12‑point design allows for easy installation with standard impact tools, reducing install time on the shop floor or trackside.

Why Choose Us

ARP has been the benchmark for performance fasteners for decades, and this bolt set reflects that heritage. The alloy steel composition is centerless‑ground to achieve near‑perfect concentricity, eliminating the risk of uneven load distribution. Each stud undergoes a proprietary heat‑treatment process that raises its fatigue life by a factor of ten compared with conventional studs, giving you confidence during extreme RPM spikes. Our quality assurance includes rigorous hardness testing (Grade 8) and a 100% inspection guarantee, ensuring every bolt meets the highest industry standards.

Key Features

• Heat‑treated 8740 alloy steel provides 220,000 psi shear strength for ultimate durability.
• 12‑point head design offers quick, secure installation with standard tools.
• Centerless grinding ensures perfect concentricity, reducing stress concentrations.
• Includes premium parallel‑ground washers and compact nuts for a complete, ready‑to‑install kit.
• Backed by ARP’s industry‑leading warranty and dedicated technical support.

FAQ

What engines are compatible with the 0.4375‑16 UNC thread size?

The 0.4375‑16 UNC thread is a common size for many American V8, V6, and high‑performance four‑cylinder engines, including popular Chevrolet, Ford, and Chrysler platforms. Always verify your engine’s head bolt pattern before purchase.

Do I need any special tools to install these studs?

No special tools are required. The 12‑point head works with standard impact wrenches or torque wrenches. Ensure you use the recommended torque specifications provided in your engine’s service manual.

How does the fatigue strength compare to standard Grade 8 bolts?

ARP’s proprietary heat‑treatment gives these studs roughly 1000% better fatigue strength than typical Grade 8 hardware, meaning they can endure many more load cycles without failure.

Is the kit suitable for street‑legal performance builds?

Yes. While engineered for competition, the studs meet all OEM specifications for strength and durability, making them ideal for street‑legal high‑performance applications.

What warranty does ARP provide for this bolt set?

ARP offers a limited lifetime warranty against material defects and includes technical support to help you with installation or fitment questions.