Billet Aluminum Fill Cap

The Billet Aluminum Fill Cap from ATL Fuel Cells is a precision-engineered fuel system component designed for high-performance vehicles and custom racing applications. Whether you're building a dedicated track car, street machine, or fuel cell-equipped drag racer, this cap provides secure, reliable sealing of fuel cell filler necks. Built from solid billet aluminum rather than stamped steel or plastic alternatives, it delivers the durability and leak resistance that serious automotive builders demand when working with pressurized fuel systems.

Machined from 6061-T6 or equivalent billet aluminum, this fill cap features a robust design that prevents fuel spillage and maintains system integrity under vibration and thermal cycling. The precision-threaded design ensures a gas-tight seal, critical for fuel cell applications where even minor leaks compromise safety and fuel economy. Its compact footprint—measuring 3.6 by 1.1 by 4 inches—allows integration into tight engine bay layouts common in modified vehicles. The lightweight construction at just 0.285 lbs contributes to overall vehicle weight reduction without sacrificing structural integrity or sealing performance.

This fill cap is ideal for restorers, race teams, and performance enthusiasts upgrading to ATL Fuel Cells racing fuel cells or compatible aftermarket fuel systems. Installation is straightforward for anyone with basic mechanical experience—simply thread onto the fuel cell filler neck and tighten until snug; over-torquing is unnecessary and can damage the aluminum threads. Direct fitment compatibility is guaranteed with ATL Fuel Cells filler neck designs, making it a drop-in upgrade for existing systems or a factory component for complete fuel cell installations. Recommended for all racing fuel cell setups, vintage street rods, and any custom fuel system requiring reliable, corrosion-resistant sealing.