Cap & Bung Assembly 3in

The Cap & Bung Assembly 3in from Peterson Fluid is a precision-engineered tank closure system designed for custom fluid reservoirs, racing applications, and high-performance engine builds. This weld-on bung and threaded cap kit is essential for builders who need reliable, leak-free tank sealing with a clean, finished appearance. Whether you're fabricating an aluminum fuel cell, coolant reservoir, or catch tank, this assembly provides the structural integrity and professional look that serious fabricators demand.

This assembly features a 3-inch outer diameter aluminum bung with welded mounting capability and a matching aluminum threaded cap finished in black anodize. The black anodized coating provides both corrosion resistance and a factory-quality aesthetic while protecting the aluminum from oxidation and fluid contamination. The threaded cap design allows secure hand-tightening without special tools, and the precision threads ensure consistent sealing across multiple open-and-close cycles without thread degradation or leakage concerns.

Fabricators, engine builders, and custom tank manufacturers benefit most from this assembly when creating billet or aluminum tanks for racing, hot-rodding, and motorsport applications. Installation requires TIG or MIG welding of the bung collar to your tank, making it ideal for shops with welding capabilities. The compact 4 x 1.25 x 4-inch footprint and lightweight 0.45-pound design make it suitable for fuel cell applications where weight and space efficiency matter. Verify tank wall thickness and material compatibility before welding to ensure optimal results.