Gas Tank Upgrade
As many of you are aware, gas tanks for the early (71-73) Mavericks and Comets are not reproduced. The later tanks are available but they have clearance problems with the rear valance panel. Another problem with the design is the way it was offset to the left to provide clearance for the muffler. This gives very little room on the left side to run an exhaust pipe for duals. The solution I found was to install an early Mustang tank. The benefits are that they are easily available. You can get a kit that includes a new tank with a drain, new sending unit, hose, and clamps for less than $150. The kits without drains are under $130. The great thing is you will have room on both sides of the tank to run 4 pipes with room to spare. I did all my modifications with normal hand tools, air powered cut off wheel, and a mig welder. A set of torches will help in reforming the tank straps but are not necessary. I bought my tank kit from CJ Poney Parts. 1-800-888-6473. You will also need some scrap 16ga steel to make some brackets and the following 2 parts from Ford. Grommet-F6TZ9B076AA, Vent Valve-E7DZ9B593A.
First thing is to acquire all your parts and remove your old tank. You also need to remove the brackets that are welded to the trunk floor that are there to keep the tank from sliding around. The left tank strap mounts can be used as is. The right strap mounts need to be moved over approximately 4 ¼ inches. The straps also need to be shortened. Use my measurements as a guide only. Every situation is a little different so double check your own measurements before cutting or welding anything.
Set the plate you made on the crossmember. Everything should be flat. This will box in the mount. There will be gaps on the sides but you can fill them in with the welder. The completed rear mount should look like this. That pretty much takes care of the hard stuff
Now we need to shorten the straps. I found the straps needed to be shortened the same length of the reinforcement plate on the bolt end. I used a torched to heat it up cherry red, flatten the end, and then bend it back over on itself, right at the edge of the doubled plate. I used the original hole to plug weld it to itself. Then all you have to do is drill a new hole and duplicate the original L shaped bend.
After you have all the mounts done, straps shortened, and brackets made, mount the tank in the car. Make sure it is as far back as it can go. The filler neck should be in the center of the opening in the trunk floor. Once the tank is mounted, take your filler neck and start cutting the bottom off a little at a time until it slides in the back panel and is no more than ¼ above the filler tube on the tank. Both tubes should line up. Make any adjustments needed and trim the connecting hose so that you have just enough overlap to put a clamp on each tube. You want to keep this connection as low as possible so that the floor seal will cover it all up when completed.
Now we need to weld the 4 brackets on. I put 2 of them in the front and one on each side. Slide them until they touch the flange of the tank and tack them in place. Then remove the tank and finish welding them.
The Next step is to install the vent fitting in the top of the tank. Mustangs use a vented cap where as Mavericks and Comets do not. We run our gas fumes out the top vent, route it into a carbon canister under the hood, and send it into the air cleaner to be burned in the engine.
Now it is time to mount the tank and hook everything up, hopefully for the last time. Do not install the sending unit yet.
The last thing to do is reroute your fuel lines and wires to the sending unit. The Maverick & Comet plug has 2 wires going to it. The Mustang sending unit only has hook up for 1. Cut the plug off the wiring harness and strip the bare the ends of insulation off the ends. Turn your key on and watch the gas gauge. Ground one of the 2 wires. If the gauge does nothing, ground the other wire. The gauge will go to full when one of the 2 wires is grounded. You will hook this wire to the connection on the sending unit. The other wire will be grounded to the gas tank. Make sure you have a good ground. Many electrical problems can be traced to bad grounding. Hook all the wires up, ground the sending unit to the tank, and check it out. Now is the time to check, not after you fill it up. If everything checks out ok, install the sending unit.
That is about all there is to it. I thought it was a fairly easy mod and the benefits are well worth it. Now get rid of those girly 2 pipes and hang some manly ones in there. If you have any questions you can Email me at Mavaholic@aol.com