Fill Cap Kit Steel 1-1/4in -1/2UNF

The MOROSO Fill Cap Kit Steel 1-1/4in -1/2UNF is a precision engineered filler neck assembly designed for high-performance engine builds and custom fuel system installations. Whether you're upgrading a classic hot rod, restoring a vintage muscle car, or fabricating a custom fuel cell setup, this steel cap kit provides a reliable, leak-free sealing solution that meets OEM-level standards. Serious builders and mechanics trust MOROSO components for their durability and fit, making this kit an essential upgrade for any fuel system requiring a 1-1/4-inch diameter opening with 1/2-inch UNF threaded connection.

Manufactured from hardened steel, this fill cap kit delivers superior corrosion resistance and longevity compared to plastic or aluminum alternatives commonly found in aftermarket systems. The 1-1/4-inch nominal diameter accommodates larger fuel filler necks typical in performance fuel tanks and custom reservoir builds, while the -1/2UNF (Unified National Fine) thread specification ensures a precise, vibration-resistant fit that won't loosen under high-performance driving conditions or fuel system pressure cycling. The compact design and 0.25 lb weight make installation straightforward without adding unnecessary mass, critical for weight-conscious builds where every pound counts in suspension geometry and overall vehicle balance.

This kit is ideal for engine builders, fuel system integrators, and restoration specialists working with aftermarket fuel tanks, fabricated fuel cells, or OEM fuel system upgrades. Its steel construction makes it particularly suited for high-heat environments near turbochargers or superchargers where plastic caps fail. Installation requires a standard 1/2-inch wrench or socket for the UNF fastener, making it compatible with any fuel system featuring a 1-1/4-inch filler neck diameter—whether you're sealing a traditional gas cap opening or integrating it into a custom pressurized fuel system. MOROSO's reputation for precision ensures compatibility with racing fuel fillers, street rod applications, and professional-grade fuel system components.