Old gas tanks are full of surprises, and those surprises are usually in the form of dirt and wasp nests . That was certainly the case with the tank of our 1941 Lincoln Continental project, despite the fuel-turned-turpentine that had been sitting in it since the mid-1950s. After cutting away the rusted straps that held the tank to the frame, there was no question it was destined for the scrap pile, as it weighed more than 50 pounds. We never planned on reusing it, but that certainly sealed its fate. Instead, we opted to go a more traditional route by installing an early Mustang fuel tank, which has been used in many Kustoms and traditional hot rods for decades.

The reason these tanks are so popular is because of their original application, which is a drop-in style through the trunk floor. Not only does this simplify the conversion, but it also eliminates several key aspects of building a custom car, such as gas-tank repairs, fuel-cell mounts, tank straps, etc. These tanks are available as brand-new reproductions, which means that they are ready to go right out of the box. However, Holley's Sniper fuel tanks come with a built-in high-pressure in-tank fuel pump, which is perfect for modern EFI systems. The engine in the Lincoln is fuel-injected, so the pump was required, but now the installation is that much easier because all we have to do is run a couple of fuel lines and a power wire for the pump. Done and done.

The installation of the tank required cutting up the floor of the trunk. As with many projects, this was already on the table, because the original floor had not only been cut for access to the fuel-sending unit, but it had also been covered in 3 inches of roofing tar, which was the late-1940s style of sound-deadening. That meant the floor was completely rotten. The original fit and finish of these cars causes severe rot from all the debris and moisture that gets in. There were full, 1-inch gaps between the trunk floor and the vertical walls of the trunk; no wonder they used so much tar and newspaper.

The floor is an odd shape, so we built a framework for the new tank to sit square and flush and then rebuilt the rusted floor around the tank. We cut out the old floor, exposing the original crossmembers that the tank was strapped to. This was our new foundation to build from. We used some strips of 16-gauge sheetmetal and a Woodward Fab sheetmetal brake to form a Z-shaped riser for the tank. The tank will sit inside the center of the riser frame, which will be lined with rivnuts (riveted, threaded inserts), making install and removal a one-person job. The rest of the process involves building a floor around the frame, which can be done a couple of different ways.

The floor skin itself is made from 18-gauge sheet—strong enough to support just about anything you would need to put in the trunk, while also being workable by hand. We roughed out the shape with a plasma torch, then used a few different techniques for bending the metal. Most of this job can be done with handtools, with the exception of the main tank riser, which requires a brake of some kind, as well as a shrinker/stretcher tool to get the curves of the trunk pan just right. You can always make a template for the riser and have it bent at your local sheetmetal supply shop for a few bucks. The shrinker/stretcher could be replaced with some extra cuts and welds, but if you are going to do any sheetmetal work, you should consider picking up a set.

The plumbing for the tank is straightforward, requiring either 3/8-inch hose barbs or, as we used, -6 AN-style fittings for a leak-proof seal. The fuel lines are now inside the vehicle, so we routed them quickly to the underside of the floorpans through a pair of -6 AN bulkhead fittings that we picked up from Summit Racing. The original filler neck ran through the driver-side rear fender, which we have welded up, so we fabricated a new filler neck using some exhaust tubing and a couple of fuel-neck couplers. The new filler neck is in the center of the Continental Kitmounted rear spare tire.

We spent the better part of two days building the frame and filling in the floorpan. Using mostly handtools and some crafty ingenuity, the new floor looks good, has full functionality, and is a far better fit than the factory floorpans: no more 1-inch gaps!