ARP M8 x 1.25 x 55 Hex Black Oxide Bolts (5/pkg)

This ARP performance fastener, stud, bolt, tool, or assembly is the M8 x 1.25 x 55 Hex Black Oxide Bolts (5/pkg). Confirm the exact engine or vehicle application, thread size, length, material, strength series, included quantity, installation lubricant, tightening sequence, and current ARP torque specification before ordering.

Key Features

• Length: 55mm delivers exact reach in manifold throttle body and valve cover mounting points.
• Material: 8740 chrome moly steel with 180000-200000 psi tensile strength handles extreme engine stresses.
• Thread Size: M8 x 1.25 matches OEM and aftermarket threaded holes for precise fit without modifications.
• Finish: Black oxide coating prevents corrosion and reduces galling for smooth repeated installations.
• Requires 13mm socket compatible with all standard tools.
• Yes ARP 661-1008 M8 x 1.25 x 55mm bolts replace OEM fasteners on B16 B18 intake manifolds throttle bodies and valve covers.

Fitment

Specifications

What’s Included

One new ARP hardware kits – other in the exact configuration and quantity identified by this listing. Brackets, wiring, air lines, fittings, switches, fasteners, fitting kits, fluids, covers, and accessories are included only when expressly stated for this exact part.

About ARP

Automotive Racing Products manufactures high-performance studs, bolts, nuts, washers, wheel hardware, assembly tools, and installation lubricants for engine, drivetrain, chassis, and racing applications. Thread dimensions, material, preload method, lubricant, torque, and included quantity remain exact-part specific.

Important Disclosures

• California Proposition 65 warning applies. Review the current manufacturer warning before handling or installation.

Related Parts

• Shop all ARP products
• ARP .875in OD x 7/16in ID Insert Washers (10 pack)
• ARP 01-06 6.6L GM Duramax Diesel Flywheel Bolt Kit
• ARP 01-10 6.6L GM Duramax Diesel Flexplate Bolt Kit

Frequently Asked Questions

How do I confirm the M8 x 1.25 x 55 Hex Black Oxide Bolts (5/pkg) fits my application?
Match the exact engine family or vehicle, component location, thread diameter and pitch, under-head length, material, strength series, and every current ARP application note.

Can I reuse the factory torque value with this ARP hardware?
Not automatically. Use ARP’s current instructions for the exact part, material, lubricant, tightening sequence, and preload method. Factory torque values may be based on different hardware and friction.

What is included with this ARP kit?
Only the studs, bolts, nuts, washers, lubricant, and tools expressly listed for this exact part number are included. Verify the required quantity before disassembly.

Installation Instructions

1. Confirm ARP part number 661-1008, the complete application, and every required supporting component before beginning work.
2. Clean and inspect all mating threads and components, then verify thread engagement, length, washers, nuts, lubricant, and required preparation before assembly.
3. Follow ARP’s current tightening sequence, lubricant instructions, torque or stretch method, and any retorque procedure for this exact part.
4. Verify clearance, preload, fastener seating, and normal component operation before returning the vehicle or engine to service.