Fuel Line size

[cazman]

I am switching over my fuel lines on my Twin cam from the stock plastic to steel.  I believe the stock fuel pump takes a 1/2-20 inverted flare fitting. And the the lines are 1/4". The tube out of the fuel tank looks like 1/4" also. The problem is that 1/2-20 goes on 5/16" tube, not 1/4". I'm I missing something? Does everyone switch to 5/16?

[4129R]

I dip a 1/4" rubber hose into boiling water to soften it, and then it stretches over the larger bore pipe needed for the fuel pump.

Don't forget to put the jubilee clips loose on the pipe first.

[jbcollier]

I ran 5/16" fuel line when I plumbed my crossflow.  Not necessary though, 1/4" would do given the short runs.

I don't like the idea of stretching 1/4" hose over 5/16" pipe.  It places the hose under severe tension and forms a natural fail point.  Use a simple reducer.  Or, solder a 1/4" nipple to the 5/16" line.

[cazman]

I read that a larger tube from tank to tank would aid in the slow transfer when filling one side. Has anyone used the larger drain plugs as the outflow and plugged the original? I suppose the factory used a outflow a bit higher on the tank as not to grab silt, but it seems doable.

[BDA]

It would but I don’t know how much. I ran AN -6 hose which is between 5/16” and 3/8” ID and I need to fill each tank separately. Obviously, the larger you go, the better it works for fill-ups but there are practical considerations to consider (that I didn’t worry about) that may or may not be easily overcome.

[cazman]

To use the fuel tank drain plug opening to feed the fuel lines, I need to figure out what kind of fitting the drain plug is. I ordered a couple of fittings from McMaster-Carr, but they were wrong. Anyone know what type of fitting these are?  Looks like the same type as a oil drain plug.

[jbcollier]

Probably BSP.

[Kendo]

The drain plug points down (duh) so fittings and fuel line could get caught by stuff one drove over. And all of the gunk in the tank would get into the line. Better have a great filter and check it regularly. On the other hand, it doesn’t modify the tank. So far the stock hose size has been fine for me. But I never raced the car, either

[cazman]

jbcollier - i think you are right. It probably is BSP. Thanks.

Kendo - if I could have gotten a elbow directly out of the tank, the lines would still be tucked up nice. But, using adapters to go from BSP, I think will be too much plumbing. So, I'll just go with the stock outlet. I am not too worried about the gunk. After 50 years, the tanks are remarkably clean and I have a pretty big filter.

[Bainford]

The problem with a large cross-over pipe that would fill both tanks simultaneously, is it does away with the twin-tank refuelling dance that curious onlookers seem to find a minor spectacle. One of those lovable quirks of Europa ownership.   

[cazman]

Well, I have hard lined everything (except rubber between the chassis and the engine) and I am up to the fuel pump. Does anyone know if the pump will take a inverted flare tube nut in place of the compression fitting that is there now?