It could have something to do with those pesky steel splinters that always impregnate themselves in your skin. Or maybe it has to do with man's natural aversion to forking over stacks of greenbacks so tall in height for products so diminutive in size. Whatever your own personal prejudice may be, no one likes plumbing. Nonetheless, proper fluid transfer keeps your motor from going poof, and keeps your car out of the sand trap. Considering the dire consequences of getting it wrong, it only makes sense to get your plumb job done right the first time. To help us accomplish this, we hit up Kevin Cochran of Earl's Performance Plumbing. High-performance plumbing has come a long way in recent years, so it's time to get up to speed. Equipping yourself with the knowledge to properly select components, size and route lines, choose the right tools, and install fittings will ensure your fluids stay off of the pavement and in your car.
Origins Of AN Fittings
"The AN (Air Corps/Navy) standards were established prior toWW II in order to organize and standardize the sizes, configurations, and specifications of military aircraft hardware into a service-wide system of interchangeable parts," Kevin explains. "Due to its simplicity and effectiveness, the system soon became industry-wide. With respect to plumbing, the number that we usually refer to as the AN number is actually a size designation and comprises only a small part of the full AN identifying number. It is properly referred to as the AN dash number, and does not define the inside diameter of a flexible hose. Instead, it refers to the outside diameter, in increments of 1/16 inch, of the metal hard line that is considered to be its equivalent in flow. The hard line outside diameter was used as the standard simply so that the metal flared tube compression sleeves and coupling nuts used with the hard lines could be standardized."
If everyone knows that 90-degree turns should be avoided when plumbing a fuel or brake system, it's probably because that bit of advice is a widespread myth. "This is only true when you can use a straight, 30- , 45-, or 60-degree fitting and choose to use a 90-degree fitting instead," explains Kevin. "Earl's second-best selling hose end is our swept tube Swivel Seal 90, a design that yields tremendous flow through the entire fitting. Also, our straight-to-low-profile 90-degree brake fitting assemblies are our second most popular configuration. Contrary to popular belief, 90-degree hose ends are an essential part of plumbing any vehicle."
Although it seems like common sense, bending hoses should be avoided whenever possible. "The number-one issue with plumbing we find is that people do not use all of the configurations of hose ends at their disposal when making assemblies," explains Kevin. "They need to let the hose end route the hose, not use straight hose ends and bend the hose, which is the reason why we offer so many different degree bends. Hose is for taking fluid from point A to point B without getting it on the ground and without considerable pressure drop. Use the different degrees of hose ends available to you to accomplish this in your routing."
To maintain top-notch product quality, Earl's has always used aircraft-quality raw material and manufactured its own parts in-house. It is all domestically sourced to control the quality demanded in racing applications. "Rigorous testing is very much part of our manufacturing process," explains Kevin. "We still pressure-test every brake line that leaves our building at 4,000 psi. We periodically test hose assemblies to the point of failure to ensure that the quality standards of the parts are being met. Our warranties amount to less than 1 percent annually, and for the number of parts Earl's ships per year, this is a testament to making a quality part from the outset."
Due to advances in fitting technology, aluminum hose ends can now be used in applications once reserved for stainless steel hose ends. However, there is still a time and place for both. "With the advent of more sophisticated plating in performance plumbing-like Earl's Ano-Tuff and Ultra-Flex hose ends-aluminum can be used in the same environments in which stainless was necessary in years past," says Kevin. "The obvious benefit of aluminum over steel is weight savings. Stainless steel has mostly been relegated to brake line and turbo systems due to their superior structural integrity and resistance to heat."
Plumbing up your ride with AN hoses and fittings is a costly affair in anyone's book, but there's a reason why racers endure the expense. "Earl's designs the majority of our parts for racing, so you are actually buying the same parts that race all around the world every week," says Kevin. "If you buy our Ano-Tuff hose ends with stainless hose or nylon fiber hose, you have a much better assembly than OE lines or what's available at your local parts store. This is due to the longer thread life of the Mil-spec Type III, Class 2 plating on the hose ends, and our high-flow synthetic rubber armored hose. It survives longer in harsher environments than a standard hose assembly, and let's face it, it just looks a hundred times better than OE lines."
To achieve the ideal balance of flow volume and pressure in a fuel system, choosing proper line diameter is critical. A good place to start is to determine the fuel flow requirements of your motor based on formulas provided by your fuel pump manufacturer. Next, pick out the right-sized line, keeping in mind that an AN-6 line will sufficiently feed the healthiest of small-blocks. "As a rule of thumb, an AN-6 hose should be used for flow rates between 1.5 and 3 gpm, an AN-8 hose for flow rates between 2.5 and 6 gpm, an AN-10 hose for flow rates between 4.5 and 10 gpm, and an AN-12 for flow rates between 7.5 and 15 gpm," explains Kevin. "You also need to make sure you find out the pump or carburetor manufacturer's recommended minimum line size for adequate fluid delivery for their products."
Steel braided lines are no longer the only game in town. Earl's introduced its Pro-Lite 350 hose-a synthetic rubber hose covered in black nylon fiber sheathing-several years ago, providing a viable alternative to steel braided lines in many applications. While stainless lines can handle greater pressure and heat, Pro-Lite 350's pressure and temperature ratings of 350 psi and 300 degrees F, respectively, are plenty stout for most hot rods. Furthermore, it offers lower abrasion qualities and greater flexibility. "A lot of which hose you choose has to do with looks, as stainless steel is more flashy and the Pro-Lite is more stealth," says Kevin. "The main advantage of Pro-Lite is how easy it is to assemble compared to stainless. It has almost no blossoming when cut and does not stick small stainless barbs in your fingers when assembling."
With all the different fuel additives that are put into pump gas these days, it's nearly impossible to make sure that your fuel lines will be compatible with modern fuels. "You could have new lines on your car for years without an issue or you could have trouble in a week," Kevin quips. "There are 23 different pump blends spread across the United States due to environmental regulations, and since most rubber hose was developed for leaded gasoline-or racing fuels in our case-the new environmental additives definitely affect the hose. That is why we clearly state in our catalog that if you do not know what the effects of gas additives will be in your area, use a Teflon hose. The plumbing market is very adaptive, though, and is already working on a hose compatible will all pump gas additives."
For those debating between barb fittings and more traditional swivel-style fittings, it's important to know the benefits and drawbacks of each. Barb fittings are easy to install, and can simply be pushed into the end of a hose. However, this comes with a significant reduction in hose end retention. With an AN-6 hose, a swivel-style fitting can handle 1,500 psi, while a barb fitting is rated at 250 psi. Still, that 250 psi rating is plenty for most fuel systems. As for swivel-style fittings, they may require more time to assemble at first, but are easier to handle later on. "The biggest benefit of our Swivel Seal fittings is that they can rotate 360 degrees on the hose ends, which means they're fully adjustable after assembly," explains Kevin. "This makes them much easier to work with and route, especially for novice plumbers. With a Swivel Seal you need to leave approximately 1/16 inch between the hex and the socket for final assembly, and with barb fittings you need to assemble it flush to the end for best retention."
"The most important thing to remember when cutting hose is to make sure it is as close to a 90-degree cut as possible," Kevin advises. "This makes it much easier to start the hose end and to help eliminate the possibility of an assembly leak in the line. Always cut the hose through the tape and make sure to remove the tape before assembling the hose end. Wrap the tape tightly so there is less chance of the sheathing 'blossoming' after the cut. Do not use a band saw with stainless steel since it can tear the outer braid if the blade is not sharp enough. Don't ever use a chisel, snips, pliers, or a shear with Teflon hose, as it crushes the liner and the hose end will never seal correctly. A sharp-bladed chop saw works great on stainless steel rubber line. A sharp, 32-teeth-per-inch hacksaw blade also works great for DIYers. If you are using removable hose ends with Teflon-lined brake and clutch hose, put the socket on the line before you cut it, making sure it is facing the correct way. This makes it extremely easy to finish the assembly by just bringing the socket up the line and screwing it onto the hose end."
Ultra-Flex 650 Hose
"Earl's Ultra-Flex 650 is our finest and lightest hose," Kevin says. "It combines a woven Kevlar braid or a high tensile 304 grade stainless braid with internal smooth-bore Teflon tubing for increased flow. Its convoluted exterior offers incredible flexibility, and its flow and pressure ratings are significantly higher than conventional convoluted Teflon hose, at 57 and 64 percent, respectively. Compared to conventional steel braided lines, Ultra-Flex 650 Kevlar is 60 percent lighter than the competition, and the 304 stainless is 40 percent lighter. On average, Ultra-Flex 650's inside diameter is 14 percent larger than standard steel braided hose, and since it is made with a Teflon tubing it has a very large range of applications including fuel, oil, water, and air. Furthermore, Ultra-Flex hose ends have been designed exclusively for this high-end hose. The crimp design offers the lightest alternative in plumbing a race engine. Every hose end is made from domestic aircraft-quality materials in Earl's manufacturing headquarters in California, and has Mil-spec Type III, Class 1 hard anodizing. Taking it a step further, we have impregnated them with liquid Teflon under vacuum to significantly reduce the friction of the fluids running through the entire line assembly."
Due to the extreme pressures involved with brake and clutch systems, using Teflon-lined hose is a must. It is the best hose for all brake fluids on the market, as not only is it lightweight and chemically inert, but when armored with stainless steel it can take any pressure involved in a brake system. "Earl's has always used stainless steel, Teflon-lined, 0.040-inch wall thickness aircraft-spec hose and we are actually the company that first brought this combination to racing back in the '60s," says Kevin. "Additionally, you must always make sure your lines are the correct length so you do not damage the line with wheel travel. This is the most common culprit found in brake line failures."
NPT VS. AN Fittings
When it comes to sealing capability and user friendliness, there is no comparison between traditional NPT fittings and AN fittings. "The biggest difference is that AN fittings utilize an O-ring or washer as a sealing mechanism, while NPT fittings rely on the threads themselves for sealing," explains Kevin. Sealing on threads is a spiral leak path, and if overtorqued it can split the housing because the threads are tapered. "Using Teflon tape to seal the NPT thread is also a messy system," Kevin says. "With AN fitting, you just screw them in, then seal on the O-ring and you're done. Using AN threads simply ensures a better and more reliable seal."
Tools Of The TradeSince plumbing fuel, brake, or nitrous systems can be tedious, having the right tools for the job is essential for a leak-free installation. Kevin suggests the following: a soft-jaw vice, a fine-bladed hacksaw or chop saw, a set of AN wrenches, a ruler and tape measure, screwdrivers, tin snips, duct tape, and assembly lube or 50-weight oil. Additionally, Earl's offers a full line of tools to further simplify the process. "We have crimpers, die sets, grooving wheels, assembly lube, tubing beaders, soft aluminum vise jaws, pressure test kits, Teflon tape, copper and nickel antiseize, AN-3 and -4 Teflon braid spreaders, single- and double-ended aluminum AN wrenches, and safety wire," Kevin says.
Mistakes To Avoid
"We come across lots of installation errors, but these are the most common," Kevin says. "People often leave insufficient clearance between each hose end and components in a car that vibrate. Also, allowing a hose to come into contact with a sharp corner, a nut, a bolt, a rivet stem, or anything else that is not smooth is something to watch out for. Preferably, a hose shouldn't rub on anything, even a flat, smooth surface. Kinking the hose, either by bending it too tightly or by placing the hose in a torsional bind is anotherno-no. Overtightening the hose ends onto their adapter fittings or into their ports should be avoided. Furthermore, hoses should not be stretched and must have enough room to flex. Also, it may seem like common sense, but never hang things like brake calipers or pressure regulators off of hoses."