Fuel System Fluids - On The Move - MMF Tech | Fluid Transfer Options

On a carbureted engine the fuel pressure may be 5-7 psi. Even with this relatively low pressure there are some things to keep in mind. Instead of using regular rubber fuel hose to install that new carburetor, a billet fuel log should be installed for a solid and leak-proof installation. BG Fuel Systems' billet aluminum fuel logs are made of aircraft-grade material. It offers spring-controlled fuel pressure at idle. They come equipped with triple O-ring seals and have provision for a fuel pressure gauge. The BG fuel logs range in price from $159 to $224.99.

This photo shows our carb set up for the BG fuel log. You can see that the result will be a rigid and solid connection for fuel at the carburetor. The AN-type connections are a far more desirable set up than a flexible rubber line with worm drive hose clamps.

On an EFI system the pressures generated are far higher than on a carbureted set up, in the 50 psi range. Hence, the use of the correct lines is even more important on an EFI system because the higher fuel pressure makes any rupture in the system far more dangerous. This is why factory EFI systems include an inertia switch to shut off the electric fuel pump in the event of a collision, something that should be included on any EFI conversion. EFI fuel pumps such as this Professional Products Power Flow EFI Blue Fuel Pump will deliver fuel at a rate of 58-gallons (220-liters) per hour. The innovative extruded aluminum heat sink helps keep the fuel cool. The pump is PN 70151 and the price $105. The late-model preformed lines, with their special connectors, are no good for a custom EFI installation on a classic Ford. To create an EFI fuel system that's up to the pressure requirements, a top-quality flexible line (or custom-formed hard line) and AN fittings can be used.

Earl's double ended hose-end wrenches will be needed to assemble the AN connections to our fittings correctly and without damage. They include a size for every AN fitting.

Here, the special AN wrenches are used to secure the fitting to the hose ends. The wrenches are made of billet aluminum so as not to scratch or otherwise damage the AN fittings. Assembling AN lines is not a black art, but it does take some practice to get it right.

These -6 AN hose-end fittings from Earl's Performance have a 90-degreee bend and are the correct size for the 3/8-inch fuel line used on our project. The AN stands for Army Navy and these fittings were developed by the military to make very reliable connections in both flexible hosing and in rigid tubing. AN sizes range from -2 to -32. Every step equates to the outside diameter of the tubing in increments of 1/16-inch. Hence, a -4 AN size would be equal to 1/4-inch OD tube (4 x 1/16 = 1/4). The AN system does not specify the inside diameter, as tubing wall thicknesses vary. AN fittings are a flared fitting and use a 37-degree flare to form a metal-metal seal. Don't try to use an AN fitting with a standard 45-degree SAE flare fitting or line, as leaks will be your only result. The following chart should help you determine which AN size you need for your application.

Here a fuel line attachment is again made using the AN wrenches. Forget any hose clamps or barbed nipples. Every fitting in the fuel system will be AN, thus eliminating any weak points in the system.

As seen here, an adapter is used between the oil filter and the cylinder block to carry the oil to the external cooler. This Boss 429 external engine oil cooler setup is shown with factory lines, but on a custom build the bulletproof aspect of AN connections and braided steel lines will give you peace of mind when running an external engine oil cooler.

There are several different types of external engine oil coolers available. This new unit is PN 29307 and comes from Performance Rod & Custom. With dual electric fan assist this is a great solution for an external cooler that can't be situated in the slipstream. Any of these external coolers require a failure-proof connection to the engine and you can see that this unit is equipped to accept AN connection fittings.

For most classic applications, OE-type coolant hoses are adequate. These exact reproduction hoses even have the original style clamps.

Those of us after a custom touch can opt for flexible radiator hoses with metal coil or braided steel jackets. This Form-A-Flex hose from Earl's is for cooling system upper or lower hose applications. Matching heater hoses can be used as well.

There is no doubt that braided steel jacketing on the upper radiator hose is a major custom touch. Matching braided equipment is also available for the heater hoses as well. Good-looking braided steel radiator hoses like these are available from Spectre Performance. They cost about $29.95 each.

This is a 20-foot roll of Russell Performance Pro Classic black high-pressure hose. It's rated to operate safely up to 350 psi and has a 1,400-psi burst rating. Since our fuel pressure will be in the 45-55 psi range, we have a huge safety margin.