Fuel System Plumbing - Plumbing automotive fluid systems with high-pressure hose and fittings is a practice that dates back to the post-war era, when GIs returning home began applying the technology they'd observed on military aircraft to their hot rods. Today, the most common use of mil-spec plumbing is stainless braided flex lines connected with AN-style fittings. This fuel system plumbing was developed for the military as a means of providing flexible fluid couplings that could be serviced in the field without the need for hydraulic machinery to create crimped hose ends while still coping with high operating pressure. Instead, a heavy-duty rubber hose is sheathed with a stainless steel braid to add burst resistance, raising the operating pressures to over 1,000 psi in many cases. To join the sections of hose, AN fittings were developed, allowing the user to insert a hose end into a fitting, which is then tightened with common hand wrenches to create a high-pressure coupling.
The stainless braided line appeals to rodders and racers alike for both its severe-duty capabilities and its appearance, but recently, the Earl's division of Holley has introduced an alternative: Pro-Lite 350 hose. The Pro-Lite hose is fabric-braided in nylon, primarily as a means of reducing the weight of the line for racing applications. Despite this, Pro-Lite maintains a 350-psi operating rating and the same temperature range as stainless (-40 degrees F to 300 degrees F). One of the fringe benefits is its ease of service, as Pro-Lite hose can be cut and assembled with less hassle than traditional stainless. For some, the appeal is purely cosmetic, as Pro-Lite's black sheath, which can be matched with black or silver fittings, can be used to create a more industrial looking fuel system plumbing.
For our fuel system plumbing, we had a carburetor to plumb, so we opted to try Pro-Lite 350 along with Earl's fittings to tie our Holley fuel pump to the carb. We've utilized some traditional red-and-blue fittings and a bit of stainless hose for this job, but by the time this hits the newsstand, Earl's should have expanded its line of Ano-Tuff hard anodized black fittings, as well as its offerings for clear-finish Auto-Fit fittings, allowing users to plumb without color if so desired. The system is easy to use and not that pricey, so maybe it's time to ditch the rubber hose and worm clamps.
