[changzuki]

Details - Exhibit #4: Fuel Tank
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Barring any unforseen circumstances, I knew Centurion was going to have to run of its life and I wanted the tank fill to be as accurate as possible... A small amount either way would change the results drastically.
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Typical refueling before and after Stage I at the Green Grand Prix is done at the local Valero station. A Green Grand Prix official fills your tank and another writes down the amount on your tech sheet. The typical way the tanks are filled is to insert the nozzle into your filler tube and let'er rip. At some point the fuel will cause the pump handle to click off, and that essentially is the end of your full up.
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Filling the tank in this way is a problem for Centurion and a possibly a problem for the pump official. Read on...
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Per the original plans, Centurion uses the original Spitfire 10 gallon fuel tank. It's just a steel tank; no internal bladder, just a rectangular 10 gallon can. Refueling the original Centurion was done from inside the car - there was no external filler.
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CrazyJerry's Centurion has the optional external fill tube located on the drivers sail panel.
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The sail panel fill tube will accept the large nozzle at the diesel pump. From experience, I know that fully squeezing the pump wide-open until the first "click off" will result in anyone within a foot or so to be wearing at least some of the diesel-deluge that's going to come out! Depending on how much "minimum cetane 40" projectiled out, would certainly skew the fuel fill results.
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What to do? Well ask for a solution and ye shall receive! Actually it was the Centurion's creator RQ Riley who provided a solution in his inaugural post on page 6 of this thread / post #60.
Fuel Economy, Hypermiling, EcoModding News and Forum - Ecomodder.com Fuel Economy Forum
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6.html#post416423
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"We disconnected the fuel line from the tank and ran a hose to the fuel pump from a beaker inside the cabin."(RQ Riley post #60)
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I learned a lot from that entire post and thought what a great idea - run an external tank! How fitting that this Centurion would use a graduated cylinder of sorts for its MPG test just as the original had done back in the early 80's!
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And while I was at it, may as well save some weight and take out the stock tank that was not going to be used.
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To pull the fuel tank is not exactly easy.. In fact, of all the things one could do with a Centurion, this would be right near the top for difficulty. You might think you could just "drop the tank" but directly underneath the tank is the Spitfire X-frame, differential and rear of the driveshaft.


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And with the rear floor storage area removed, the buggy spring and differential frame support also are in the way..
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How about removing the rear wheel and sliding it sidways to freedom? Another detour - Ummm, fraid not...
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The body needs to be unbolted and then raise the rear off the frame until the tank is free. The tank can then come right out through the removed rear floor storage area. It may be able to come out through the wheel well too with a little finaggling. (So make sure your tank is excellent if you plan on building a Centurion)..
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Knowing the procedure makes things a bit easier and replacing the tank wasn't as much of a big-deal but I'd rather not ever have to do it again.
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It would've been really cool to leave to 2 gallon tank in...


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But it's waayyyyy cooler to be able to tell folks that I could go through all of June, July, and August before a fill-up was needed if using Centurion just for the work commute (30 miles round trip daily)...
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Another piece covered, and more to be uncovered....
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~CrazyJerry