420motorsport. Fittings & Hoses – AN Fittings, Clamps and Valves

How the plumbing system fits together

A line system for fuel, oil, coolant or vacuum typically consists of three parts: the hose or hard line itself, the fittings and plugs that connect the line to the pump, filter or carburettor, and the clamps and brackets that hold it in place. Check valves control the direction of flow, while shut-off valves close off a line. If you don't want to build everything from scratch, there are complete fuel system kits, e.g. DeatschWerks 6AN PTFE Fuel Line Kit for 4160-style carburettors with pressure gauge.

How to choose hoses and fittings

Start with the fluid, the pressure and the temperature. PTFE hoses are typically used for fuel, but whether a hose suits your fuel depends on the manufacturer's specification for that particular hose. Then choose the size based on the engine's flow requirements and the space you have for routing – a larger size is not automatically better.

AN size: e.g. 6AN, 8AN or 10AN must match the hose, the fittings and the component ports.

Thread type: AN, NPT, ORB and SAE seal in different ways and require an adapter to connect, e.g. Radium Engineering 10AN ORB to 6AN Male Fitting or DeatschWerks 8AN Long to 7/8-20 Carb Adapter for the carburettor inlet.

Angle and design: 90-degree fittings and swivel banjo fittings can shorten line runs and make installation easier in tight spaces.

Material and finish: must suit the fluid, the temperature and the rest of the system.

Installation and safe routing

Route the lines away from the exhaust manifold, moving parts and sharp edges, and secure them so vibration doesn't wear the hose. For this you use hose clamps and brackets, e.g. Russell Line Clamp, while protective sleeving such as Convoluted Tubing can shield against chafing. Follow the manufacturer's instructions when assembling fittings onto the hose, and pressure test the system before starting the engine. Check the connections after the first drives and then regularly for moisture, cracks and loose clamps. In this category you will find brands such as Gates, Fragola, DFC, Russell and Vibrant.

Frequently asked questions

Can I mix AN, NPT and ORB fittings?

Not directly. The thread types are different and each seals in its own way. You need an adapter with the correct type at both ends, and you should check that the sizes match both the hose and the component.

Which hose should I use for fuel?

It depends on the fuel type, pressure and temperature. PTFE hoses are typically used for fuel, but always check the manufacturer's specification for the specific hose, especially if you run ethanol-blended fuel.

How do I find the right AN size?

Look at the engine's fuel requirements, the pump and filter ports and the manufacturer's recommendation. Hose, fittings and components must match throughout the whole system; a larger size does not automatically give a better result.

Can I modify the fuel lines on a road car?

It depends on the product and the car. Check the inspection requirements and any approval for the specific part number, and make sure the lines are properly secured and routed safely away from heat and moving parts.