Fuel Bowl Fitting 5/8-18 w/Small Hex

The Fuel Bowl Fitting 5/8-18 w/Small Hex from Holley is a precision adapter designed for fuel system applications requiring reliable, leak-free connections between carburetor fuel bowls and supply lines. This straight fitting serves as a critical junction point in high-performance fuel delivery systems, where secure fastening and proper thread engagement directly impact system integrity and safety. Fuel system builders and engine enthusiasts rely on Holley's fitting solutions to maintain consistent fuel delivery in race cars, street rods, and modified engines where fuel system reliability is non-negotiable.

Engineered with a 5/8-18 inverted flare female thread on one end and a 7/8-20 male thread on the opposite end, this adapter accommodates mixed thread specifications common in fuel system retrofits and performance builds. The fitting features a small hex body design, enabling wrench access in tight engine bay environments without requiring excessive clearance. Constructed from steel and finished with zinc oxide coating, the material selection provides corrosion resistance and durability in fuel-exposed environments while maintaining strength under system pressure. The included crush washer ensures proper sealing and prevents fuel seepage at the connection point—a critical detail that separates quality fittings from inferior alternatives.

This fitting is ideal for carburetor fuel bowl connections, fuel line adapters, and custom fuel system configurations where thread size conversion is necessary. Installation requires proper torque specification to seat the crush washer correctly without over-tightening, which can damage the flare. The compact 3.5-inch length and lightweight 0.08-pound design make it suitable for installation in space-constrained applications typical of engine compartments. Builders using Holley carburetors or similar fuel system components with mixed thread ports will find this adapter essential for achieving professional, leak-free fuel delivery.