In competitive outboard racing environments—especially those using early Mercury Racing 12-inch midsections—fastener reliability is critical. These "studs-up" midsections, used extensively in F1 tunnel hulls, SST-120, SST-140, and drag configurations with billet transom brackets, demand a mechanical connection capable of maintaining clamp load under severe thermal and dynamic stress.
Our ARP stud kit, replacing the Mercury PowerHead Stud OEM Part Number 16-37653, addresses this with a precise, serviceable solution built around race-grade manufacturing standards.
The included ARP studs are manufactured in the USA using aerospace-grade alloy steel with a tensile strength suitable for sustained cyclic loading. Threads are rolled after heat treatment to eliminate stress risers and improve fatigue resistance.
Each stud is centerless ground to maintain strict concentricity, ensuring uniform preload across all fastening points. The result is a dimensional and structural consistency that cannot be achieved with standard hardware or rebranded industrial fasteners.
To facilitate controlled installation and repeatable service work, each stud is broached with an internal hex. This design allows accurate seating without relying on jam nuts or external tools that risk damaging threads in the aluminum exhaust housing.
The Allen interface also provides reliable removal access during midsection rebuilds or powerhead swaps, making the hardware especially suited for race programs with tight maintenance intervals.
Eight extra-thick, hardened stainless steel washers are included, each compatible with original Mercury Racing specifications. These are cross-referenced with part numbers such as 12-70833, 12-45175, 12-F1778, 2550W23059, 856774, and others, and are selected for their hardness and thickness to prevent deformation or fretting at the powerhead flange. Proper load distribution through these washers is essential in maintaining the integrity of the aluminum mating surfaces, particularly under repeated torque cycling.
Securing the system are eight prevailing-torque stainless steel lock nuts. Chosen for their mechanical reliability in high-vibration marine environments, these fasteners retain clamping force through thermal shifts and prolonged operation.
The stud length is ~ 2-11/16 inches, matching Mercury’s original specification for part number 16-37653 8. Thread pitch conforms to factory standards—coarse at the block interface for secure engagement in aluminum, and fine at the nut interface to permit smooth, accurate torque application and maintain consistent preload.
This kit is crafted for compatibility with early Mercury Racing 12-inch midsections using the upward stud mounting pattern. It is suitable for use with 2.0-liter, 2.4-liter, and 2.5-liter powerheads in SST-120, SST-140, F1, and drag racing applications, including those using aftermarket billet brackets.
It is specifically tailored for service environments where powerheads are installed and removed frequently, or where fastener integrity must be maintained without compromise under race conditions.
Buckshot Racing’s ARP stud kit represents a clean, functional solution to the mechanical demands of high-output Mercury Racing platforms. Designed for repeatable use and long-term structural stability, it meets the technical expectations of competitive marine engine builders and technicians who require accuracy, durability, and proper engineering from every component.
Note: Chromoly steel offers excellent strength and fatigue resistance, making it ideal for high-stress marine applications, but it is not corrosion-proof. In saltwater environments, it’s important to protect exposed threads with marine anti-seize or light grease, rinse components with WD-40 after use, and avoid prolonged exposure to moisture. Regular inspection and reapplication of protectant during service intervals will help prevent oxidation and ensure long-term performance.
For technical support, contact Mike Hill at +1-714-697-1716 or mike@buckshotracing77.com