Inverted Flare Union 4pk 5/16in Line 1/2-20

The Inverted Flare Union 4pk 5/16in Line 1/2-20 from ALLSTAR PERFORMANCE is a critical fluid-line connector designed for fuel, oil, coolant, and brake system applications in high-performance and custom vehicles. These fittings are essential for builders and mechanics who demand reliability when fabricating custom plumbing layouts or upgrading fuel and cooling systems on street rods, race cars, and modified engines. A four-pack format provides multiple connection points for a single project or spares for future builds.

Each union features an inverted (AN) flare design that accepts a 5/16-inch hose line with a 1/2-20 thread connection, a standard pairing in automotive fuel and cooling circuits. The inverted flare geometry creates a metal-to-metal seal when the fitting nut is torqued down, eliminating reliance on rubber washers and providing superior vibration resistance compared to straight thread fittings. The construction withstands repeated thermal cycling and pressure fluctuation without degrading, making these unions suitable for both carburetor fuel systems and modern fuel-injection setups operating at higher pressures.

Whether you're assembling a vintage hot rod fuel system, upgrading a race engine's coolant distribution, or custom-fabricating hydraulic lines for a manual clutch conversion, these fittings integrate seamlessly into industry-standard AN plumbing. Torque the 1/2-20 nut to spec—typically 15–25 ft-lbs depending on material and pressure requirements. This ensures a secure and reliable connection for your automotive applications.