ARP header bolts 3/8" hex-head set — 16-piece 8740 chrome-moly, 170,000 psi, black oxide

These ARP 100-1110 header bolts are a 16-piece, 3/8" hex-head kit made from heat-treated 8740 chrome-moly steel with a black oxide finish and a 170,000 psi tensile rating for secure, long-lasting exhaust header installs.

If you’re fitting or replacing exhaust headers, the fasteners you choose affect clamping reliability and long-term resistance to high temperatures and vibration. ARP manufactures its own hardware in-house to maintain tight tolerances and consistent quality; this set of 16 header bolts includes premium washers and is engineered for strength and repeatable torque values during installation.

Why choose these bolts over standard Grade 8 fasteners?

ARP 100-1110 bolts are made from heat-treated 8740 chrome-moly steel, delivering a much higher tensile strength than typical Grade 8 hardware. The elevated 170,000 psi rating increases margin against stretch or failure under header thermal cycles and engine vibration.

• 170,000 psi tensile strength—significantly above Grade 8
• Chrome-moly construction for superior fatigue resistance
• Black oxide finish for basic corrosion protection and reduced glare

How do these bolts help during installation and maintenance?

The hex-style heads provide a conventional wrenching surface that most mechanics and enthusiasts prefer for easy access in tight header flanges. The 1.000" under-head length positions the fastener properly for common header flange thicknesses, while included washers protect the flange and distribute clamping load evenly.

• Traditional hex heads for simple wrench or socket use
• 1.000" under-head length suited to most header flange assemblies
• Premium washers included to prevent flange damage and reduce loosening

Are these bolts compatible with high-heat exhaust environments?

Yes—8740 chrome-moly steel and the heat-treatment process give the fasteners improved strength retention at elevated temperatures compared with standard steel. The black oxide surface finish offers a degree of corrosion resistance, but for extreme or long-term exposure you may choose additional coatings or anti-seize for enhanced protection.

• Heat-treated material maintains clamping force in hot environments
• Black oxide finish reduces surface oxidation and thread galling
• Works well with anti-seize or high-temp thread compounds if desired

What are the key specifications I should know before ordering?

This kit contains 16 bolts sized 3/8" in diameter, each with a 1.000" under-head length and traditional hex heads. The set ships with matching premium washers and is labeled as ARP part 100-1110 (1001110).

• Quantity: 16 pieces including premium washers
• Diameter: 3/8"; under-head length: 1.000"
• Material: heat-treated 8740 chrome-moly steel with black oxide finish

Who is this for: This ARP header bolt set is aimed at professional mechanics, performance builders, and DIY enthusiasts who demand higher-strength fasteners for exhaust header installations. If you want bolts that tolerate high temperatures, resist fatigue, and provide consistent torque during assembly, this kit offers an upgrade over conventional hardware. For extreme corrosion environments or specialty motorsport builds, consider additional coatings or consult installation guidelines for the proper thread lubricants and torque specs.