I bent up the 14ga. tin and had my boy weld the seams. pressure tested and no leaks. It's cheaper but in hindsight finding fuel cells the same size is easier.
A friend of mine needed a tank for his 23 T Track Car project in 1969 and ended up making one of fibreglass over a hardware cloth structure. The tank has provision for fuel sender and fuel line starting about 3 inches from the tank floor and up through the top of the tank. The filler comes out at an angle and can be easily filled after opening the deck lid. The tank is contoured at the front to fit the curve of the rear of the roadster body, extends over the frame rails and sits on the frame rails. The tank has leather pads where the frame rails touch the tank. It holds 12.5 gallons. It is retained to the frame by seatbelt straps. Car is still his and tank is still great.
have made quite a few tig weld is better but mig is fine. with a mig you tend to get a pin hole where you start and stop if you don'twatch your overlaps on the weld. pressure test when done....no prob
I built a bike one... I would stay away from fiberglass, ethanol has a habit of turning them into goo. If you do go fiberglass get the best resin for it (something-ester I forget which) and you still may have to seal it with a specialty sealer. If you weld one up, put some low pressure air in when done, get a spray bottle with soapy water and spray the outside for pinhole leak testing.
I have built several steel tanks. Primarily to fit spaces that I could not buy a tank to fit or was just too cheap to pay the high price for an already built one. Worst part was getting all the pin holes filled so that there were no leaks. It just takes patience. I have purchased some pretty cool reasonably priced aluminum fuel tanks out of some marine catalogs. Finding the size is the problem.
http://www.jalopyjournal.com/forum/showthread.php?t=38970 Built one from stainless, and made nice rounded corners, beads rolled into it, not just a square box.
I made a tank for a roadster that went from inside frame to frame, the top and rear were flat, the front conformed to the body. I made it out of paperboard first, then had 16 GA. metal sheared and bent. Both ends and the bottom was one piece, front, rear, and top was the other, two baffles inside, and it was gas welded. Ten PSI inside and soapy water on the welds, then rattle can epoxy primer.
I built mine from aluminum and then filled with water and checked for pin hole leaks, and there were some! did that several times and now have run it for several years with out problem. You should probably think about some sort of internal baffles and also make sure that the point that you pick to connect the fuel out let is a low spot. Plan your take to meet the needs of your fuel system, especially if you happen to be running electronic injection you will probably need a return connection. Plan first and then fabricate as it is a pan in the ass to add things afterward. Rex
If your tank is going to be square, or rectangle shape, look at post#2, the way Chaddilac did his, with the top and ends, with formed flanges going inward, the weld seams will be much stronger, and less likely to crack over time, than a "corner to corner" weld.
I have done three aluminum cells, and pressure tested each one and fixed my pinholes and was good to go. the only reason I made them, is because they were for a custom boat and needed special dimensions to fit in the space. If you can find a pre made cell to fit, it is probably the same money as building one for a lot less effort.
I built these out of 14 ga stainless, as others have said, plan it out well, with cardboard samples, make sure of your placement of mounts, plumbing, and fill neck (with proper drop) and vent, to make filling it easy. This one was a tough one, with the duel tanks and rear seat, filling through the rear.
I have built several. I would recommend stainless steel, 18 gauge or what ever you are comfortable welding. Also TIG over MIG any day. Don't forget baffles, depending on how big your tank will be. You can buy filler necks or sending unit flanges from several places, much easier than fabricating them, SS is a bitch to cut, drill and tap. Having a friend with a sheet metal brake helps or if you have a sheet metal shop close by they might bend it up for you.
The first time I made the mistake of using ordinary body metal. It rusted up quickly. If I was going to do it again I would use galvanized steel and solder the seams. But there are so many different tanks available it is easier to buy one.
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