Would you feed your baby with an old and dirty bottle? Probably not. So if you’re thinking of rebuilding your motor or maybe putting in a newer LS then don’t forget about what’s feeding it. Simply put, your engine gives you exactly what it gets so feed it properly.
They say that the heart of a car is its engine, but far too often we’ve seen people get so lost in the chroming, polishing and engine accessories that they forget what feeds it. Now look, we understand that it’s easy to get lost in the glitz and glamour of aftermarket pullies, superchargers, steel braided lines and all that good stuff, but without the proper fuel delivery you’re left with nothing short of a big ass paperweight.
That said, it’s important you pay close attention to your fuel system. We’ve seen our fair share of people install new motors (or refresh old ones) and fail to do the same for the fuel system. Simply put, the motor is your world, and just like the world, it gives you back what you put into it.
There’s many things to consider when revamping your fuel sytem. From replacing lines, to flushing out gas tanks and resealing them, there’s a ton of things you can do but in this article we’ll go over the basics.
Now if you’re going EFI (Electronic Fuel Injection), the first you need to understand is that you will need the appropriate electric fuel pump. While there’s plenty of options, be sure to choose an inline pump which was built for your specific application. Now when it comes to buying components for your build here’s a few things to consider:
INTERNAL vs. EXTERNAL:
When it comes time to buy a fuel pump you have two options: 1) Internal or 2) External. External pumps are typically much easier to install but using an internal fuel pump has it’s advantages. For starters, a submerged fuel pump will run cooler, which translates to longer life and of course pump noise is reduced dramatically. In addition there is less chance of starvation with an internal pump. Here’s a few other factors to consider:
- In-tank pumps may also be used with carbureted systems. Depending on the pump used a fuel-pressure regulator may also be required.
- Most low-pressure pumps for carbureted systems are internally regulated to around 7 psi.
- High-pressure pumps for carburetor or fuel-injection applications often require a regulator—most are adjustable to provide the proper pressure for the application.
- The system shown here has an Aeromotive 340 in-tank fuel pump with a regulator that includes a return line and a port for a pressure gauge.
You need to understand that fuel has contaminants that needs to filtered out. These particles can come from the gas station tanks, the erosion of your own tank, dirty lines and the list goes on. Filters rated by the size of contaminates they will trap (a micron is 1/1000 of a millimeter or 0.00003937 of an inch).
Aeromotive recommends that 100-micron stainless steel filter elements be used on the suction side of the fuel pump. On the outlet Aeromotive recommends a 10-micron fabric filter (the saying is suck through stainless, push through paper). The reasoning behind this is simple. Electric fuel pumps are fairly forgiving of small particles, but what they don’t like is pulling against restrictions to flow. That causes the pump to cavitate, which normally results in a noisy pump that growls in protest and wears out quickly.
Once all the components are decided on, it’s time to figure out hot to connect them all. There are several ways to go—standard automotive rigid lines, fuel hose, inverted flare, and pipe fittings are the most economical, AN fittings and braided hose are a little more spendy but trick looking (the reference “AN” stands for Army/Navy and it was a system devised by the government to ensure interchangeability and compatibility of parts made by various manufacturers). In many cases (ours included) a combination of these components will be used so it is critical that the connections are compatible.
- Conventional automotive lines use 45-degree double flares and inverted flare fittings while AN lines and fittings use 37-degree single flares (another application of 37-degree flares will be found on JIC hydraulic fittings).
- AN fittings are often found in combination with pipe and inverted flare fittings, which means special adapters readily available from Aeromotive will be required.
- Another important distinction when using AN fittings is port threads, such as those that may be found on filters and other components, are not NPT or “pipe thread.”
- These connections have straight threads (like any normal fastener) and use SAE O-ring Boss (ORB) technology for sealing. ORB ports and adapter fittings are measured in inch/fractional sizes. AN system lines and fittings are identified by a system that uses a dash and number, such as -6. The number after the dash indicates the internal size of the components in increments of 1/16 inch. As an example a -6 line is 6/16, or 3/8 inch.
SEAL THE DEAL
No discussion of plumbing any kind of a fluid system would be complete without including Teflon tape. Teflon tape or Teflon-based sealing compound is often used on pipe threads as it can prevent leaks, make it easier to tighten fittings and disassemble them later and it can reduce/eliminate thread galling and protect fasteners made from corrosion. However, properly flared and installed SAE and AN fittings should seal by themselves and Teflon tape should not be used. In such cases the flared components make the seal, not the threads.