1968 Dodge Polara C-Body Gas tank conversion

The pipe construction/materials sound awesome for this use, and bypasses the rust concern.
But I would not route it that way, here's my rationale:
  • That's an awfully long run of pipe.
  • It's going to route thru your tailpipe area (I assume you'll have dual exh) and make routing a tailpipe harder, then you hafta make the other side match that one (could be double-trouble).
  • Biggest reason - you'll likely not have a good downhill run for the entire length of pipe, specifically by the gas tank, and if you don't, that will probably make a low spot that is lower than the tank inlet behind the license plate. You want the entire run of pipe to be higher than the tank inlet so that you never have a puddle of gas in a low spot. As the tank's original inlet is in the top half of the tank (and it's a much shallower stamping than the bottom), I don't think you can get a downhill angle while you're running beside the tank. You don't want a P-trap.

You hafta penetrate the trunk are no matter how you install this cap, so I would recommend the shortest, steepest run possible.

Perhaps you could incorporate the tank inlet into a fitting into the fuel sending unit? Whatever that is would need to outflow a gas-station pump, though, and that'll be tough with only head pressure of the fuel.

Or maybe weld a dedicated flange/nipple onto the vertical section of tank to the driverside of the fuel sender, that connects to your filler tube via a rubber coupling?

Or here's a crazy idea, way outside the box. It solves some issues (allows you to use smaller hose) but creates new hurdles:
  • Pipe the fuel filler tube into a 'catch can', install an electric pump in the shock absorber area below it, pump the fuel into the tank into a #8 fitting in your fuel sender, or maybe a #10-#12 bulkhead fitting in the tank beside the sender. Or run that back into the original filler neck somehow.
  • The catch can could be just a large section of pipe with a fitting at the bottom, and you have a switch located in the trunk hinge area to run the pump while you fill up.
  • The big problem there is making sure you don't under-pump the catchcan and splash gas on yourself, or overpump it and run the elec pump dry too often. Theoretically the gas station pump should shut off and not splash you, but we know that isn't 100% trustworthy.
  • With this idea, again, think FMEA big-time.
Good thought overall! We are going to start at the cap with a 14 inch drop to a 45% fitting and grade that at 1/4 to the foot. Should have plenty of flow to stop splash back. We modified the stock 70 Charger filler neck tube.
 
I'm totally intrigued by this kind of "out of the box" thinking, how is it coming along?
 
Back
Top