Fuel system

[71chmark]

I'm going to take off my fuel tank to my 71 challenger. Car has sat for a couple of years.  Smells like varnish inside.  Think I should replace it?  There is a place in town that will clean and coat it.  Was a 318 car so I think I'll update to a 3/8" line since I'm putting a 440 in it.  It's probably cruddy inside anyways.  I'm not planning on using the return line so I'll just leave it as is.  Looks like a pain dealing with the vent hoses. I think I can just pop them off and back on (probably have to change the clamps).  Anyone have any advice about any part of this project?

[JRoss22]

Make sure you have an extra hand helping you 

[Cuda Cody]

Not sure on the 71's but I think there are 4 lines (2 bigger and 2 smaller ones) on the drivers side of the tank.  Those are for the emissions.  You can just take them off at the tank and try to reuse them.  If you do reuse them get new hose clamps.  The other side of the tank (passenger) should have the fule line, fuel gauge wire and the ground strap.  I would use a new piece of rubber fuel line (it's short) on this side to connect to your new metal fuel line.  The rest is pretty easy.  It helps if you can get most of the old gas out.  The tanks are fairly light when empty.

The fuel line can be a bit of a hassle to get out because it weaves through the frame.  I'm going from memory from one I did on a 71 B body, so yours might be different.

Let me know if you have any more Qs.   

[Bullitt-]

I was faced with similar issues and decided a new tank was the more economical way to go.      But check with radiator shops for cleaning, motorcycle shops for sealing, hopefully you just need cleaning. 

[MEK-Dangerfield]

You can get gas tanks for less than $200, so I'm not sure I would even mess with the old one. To go to a larger fuel line(3/8), you will need a new sending unit in the tank. As Cody mentioned, these lines are a pain to weave in. You will need to take off the passenger's side rear tire to give you some help. There are also clips along the way that you will need to replace to fit the larger fuel line. You will see them when you remove the original. I started at the rear tire there and fed the first half thru the frame up to the engine. Then the back part took some messaging up thru the wheel well, and over the front of the gas tank. FYI, I did this on a 70 Challenger that had no return lines. Maybe you want to do away with those to make it easier?  I have a 440, and stayed with the 5/16 line, and I have no trouble with a hi-volume fuel pump helping me out. If you intend to race, then maybe you need the 3/8 line.


  Mike

[71chmark]

I like the idea of getting rid of the return line.  I would like to get rid of all that extra vapor recovery stuff.  Is your vent in your filler neck?  I have read in magazine articles that a 440 should have a 3/8 line (supposedly this is how the factory did it).  If I'm to change the tank and line I probably should change the sending unit also and I might as well get the bigger line in less there is some reason why not. Thanks for your input it is greatly appreciated.

[Bullitt-]

Don't forget to get a new filler neck seal & sending unit "sock" filter.

[gomopar440]

We had this discussion on another Mopar board a while back and came to this conclusion: If you completely remove all the return lines, you will increase your chances of running into vapor lock issues. You should keep one in there.

As I understand it, the fuel in the lines expands as it heats up from under hood heat and needs somewhere to go. If there's no return path, you get vapor lock. You don't need all the extra lines like on the 72-74 gas tanks though. Those don't really do anything worthwile for your engine. 

EDIT: I found the thread.  http://www.moparnuts.com/forums/showthread.php?t=5634&highlight=vapor+lock+return+line  The really good tech info starts on post #7. Doc Jass is Moparnuts version of Chryco and I've rarely ever seen him be wrong about any tech info.

[ShelbyDogg]

Without reading that post above this, I install the 3/8 pickup and new 3/8 return line. I also add the vapor separator and return line at the fuel pump. You could use the old 5/16 line as a return line if you don't want to buy a new 1/4 line.

I have 2 used tanks at home that I'm cleaning out. Most places won't boil them out because there is an internal tank inside.  To clean out the old varnish-gas inside, I'm going to buy a gallon of laquer thinner or mineral spirits and dump the whole gallon inside to wash it out.  Once I get most of the stink out, I'm going to the quarter car was to hose the whole thing out. Once you take out the sender and filler tube, you cam see the entire insides to clean out. One of my tanks, left to dry in the heat, dried all of the brown goo to the point that it's all flaking off like corn flakes. I'm going to drop a small chain in there and shake it to scrub the bottom clean.

Be carefull when working with flammable liquids!