A Tech Tip From Performance Online: No-Weld Fuel Tank Bungs

So, you’ve got a new-fangled electronic fuel injection kit from any number of manufacturers, and you’re ready to install it and reap the benefits of having a modern fuel system in your classic car. But not so fast, Performance Online has a quick tech tip that will make your life a whole lot easier.

The only problem with your project is; you’ve already dropped some serious coin on the new EFI unit and a few accessories. Now, you have to figure out whether you’re going to buy a whole new, purpose-built fuel tank or a surge pump to accommodate the new high-pressure EFI system – but, that requires modification to the existing tank or a larger bank account. The last thing you want to do is plop down more hard-earned greenbacks on a brand new fuel tank, especially when you’ve got a perfectly good one sitting under your trunk.

So, what’s a person to do? Well, you can either bite-the-bullet and pony up the dough for that fresh new tank — which is probably the best option if you can manage it. Of course, you can always drop your stock tank, empty it, flush it, and pay to have a bung welded in place. Unless, of course, you know how to do it yourself without blowing your garage sky-high.

The other option is as simple as it is clever, albeit, often overlooked. The folks at Performance Online even put together a quick “how-to” to show just how simple and easy it is.

In the video above, they walk you through how to install a “no-weld” nutsert-style bung in your factory gas tank. The process involves a minimal amount of hardware and basic expertise to accomplish the job.

What You’ll Need:

  1. Punch and Hammer
  2. Drill
  3. Step Bit
  4. 1-inch Wrench
  5. 9/16-inch Wrench
  6. Anti-Seize & Grease

Installation Procedures: 

1. remove the supplied AN- fitting, bolt, and washer.

For Step-1, you’ll want to remove the supplied AN- fitting, bolt, and washer in preparation to install the new bung. Once you’ve located the fuel pickup on the tank, you can use that to find a location for your new bung. It will likely be on the opposite side of the tank, to prevent any disruption to the pickup caused by the flow of return-fuel.

2. Apply grease to the step bit to avoid contaminating the inside of the tank with metal shavings and to prevent any warpage or twisting of the thin sheet metal.

Step-2 requires the use of grease, a step-bit, and a drill. The step-bit allows you to gradually drill the hole for your new fitting without catching the thin sheet-metal and twisting, whilst simultaneously catching most of the shavings in the grease.

3. Mark your location with a punch and hammer and drill the opening to 1/2-inch with a step-bit.

Step-3 is a simple one, but requires precision. The old adage, “measure twice – cut once,” rings true, here. Once you’ve found your desired location, mark the spot with a punch and begin drilling with the step bit. The grease should catch most of the shavings and save you the hassle of having to flush the tank or clogging the pickup.

4. Clean the surface of any debris or burrs and slide the new bung into the hole.

Step-4 is a quick and important one – clean the surface of any burrs or debris and insert the bung. You want a clean surface to work with so the bung seats flush and proper. Also, you want to keep the shavings clear of the inside of the tank to prevent any problems with the pickup.

5. The application of anti-seize will prevent dissimilar metals from galling. The bung is aluminum which is much softer than the steel bolt.

Now that the bung is in place, you’re ready to secure it. Put that welder away, and instead, reach for your wrenches. But first, step-5. Apply some anti-seize to the bolt. Since the bung is aluminum and the bolt is steel, the dissimilar metals have a high chance of galling – the anti-seize should prevent that.

6. Using the 1/2-inch wrench to secure the bung, tighten the bolt with the 9/16-inch wrench until you feel the bung collapse and flatten inside the tank, thus securing itself.

Step-6 is possibly the most satisfying of them all. Using the 1-inch wrench to secure the bung, rotate the bolt with the 9/16-inch wrench to collapse the bung and press against the inside of the tank. When the bolt is difficult to rotate, the bung is firmly seated.

7. After removing the bolt and washer, you can install the -6 ORB fitting in its place. Now you are ready to plumb the rest of your fuel system.

The seventh and final step requires you remove the bolt and install the -6 ORB return fitting using the same two-wrench method as before. Below is a photo of a tank cross-section with the new bung and return fitting installed.

Your installation is complete and you are ready to plumb your new high-pressure fuel system.

So, if you’re on a budget and don’t have access to a welder — or simply don’t want to risk blowing up your garage — consider this quick tech tip from Performance Online. You can find more quick tips like this one from POL on its website, here.

Article Sources

About the author

Vinny Costa

Fast cars, motorcycles, and loud music are what get Vinny’s blood pumping. Catch him behind the wheel of his ’68 Firebird. Chances are, Black Sabbath will be playing in the background.
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