Upgraded B58 Girdle and Oil Pump Bolts

The OE (Original Equipment) B58 Fasteners are TTY (Torque to Yield); a method that is economical to produce in large quantities with moderate material standards. This fastening technique allows each fastener to reach its maximum theoretical elongation, thereby providing maximum clamping force based on that material's property and strength.

However, a significant issue with this method is the fasteners' non-reusability. Additionally, upon close examination of clamp load, it becomes evident that two fasteners positioned adjacently do not apply the same amount of force, which is problematic. If we cannot rely on the even distribution of load, we cannot trust these fasteners—as evidenced by the failures we are observing. Another concern is the availability of replacements, indicating that many of these fasteners are not being replaced during engine rebuilds.

While the OE B58 Girdle fasteners may suffice for original equipment properties, they fall short for enhanced output. In higher power engines, we are noting fretting transfer on the main caps, between the caps and the girdle. Our upgraded hardware addresses these issues by preventing movement, making these fasteners essential for high-performance B58 engines.

The bolts are specifically designed to:

• Support the load and tensile requirements for increased output.
• Attain ASTM conformance certification. All materials must align with AMS raw materials batch standards.
• Feature optimized thread engagement and shank length for each specific bolt location.
• Meet or exceed a minimum tensile strength of 190kpsi.
• Be custom age-hardened.
• Offer corrosion resistance without any coatings or plating that could wear or degrade.
• Be indefinitely reusable unless stretched beyond the acceptable elongation limit.

This kit includes 20 bolts; apply a dab of engine oil and torque each to 30 ft-lb.

Additional Information:

The ARP-661-1004 is an appropriate fastener for stock engine rebuilds as a replacement for the OE ones.

The factory specification, utilizing a 10.9 or 12.9 PSEUDO non-graded batch fastener, is 15nm + 45 degrees, equating to a torque value of approximately 25-35nm. However, this does not necessarily reflect the capability for effective clamp load. In other words, a higher torque rating does not guarantee effectiveness. The ARP equivalent (ARP-661-1004) made of 8740 chromoly has a maximum rating of 170Kpsi. Yet our testing indicates a nominal rating of 120Kpsi on one side and a maximum yield strength of 170Kpsi on the other. All 8740 fasteners lack ASTM ratings, so their performance lies anywhere between 120-170Kpsi.

The Visconti fastener also has a rated range, but we advertise only the lower end that is ASTM certified, between 190-210Kpsi.

If there were an ARP equivalent fastener, it would be between ARP 2000 and L19, costing approximately $50 per fastener.

Furthermore, the Visconti fastener is not an outright replica of the OE design. It features a redesigned shoulder radial width and engagement which is functional to retain while allowing some conform-ability.