Does anybody have the absolute right answer for the exact 914 fuel lines diameter? On '73 1.7, the line that going from the outlet of the fuel tank, pass through the center tunnel and feed the fuel filter is 9mm (according to some litterature). Therefore, in the real life, the inlet (and the outlet as well) of the fuel filter is 7mm (for a '73). My concern is why the ''feed'' line would be 9mm if the flow is chocked anyway across the fuel filter... It makes no sense for me. In an other hand, the return line and all the fuel hoses running on the engine, including the bended elbows to the injectors is supposed to be 7mm. Right?

I'll have to install new fuel lines next days. I will take the way of using galvanised steel rigid lines. But the classical question is, where can I find metric lines? I can use for sure 1/4'' (6.35mm) for the return and 3/8'' (9.53mm) for the feed. Does it sounds good?

Thanks

IIRC, 5/16" is the preferred inch substitute for the ~7mm OD line.

I don't know why Porsche used a larger line for the feed; possibly just so they could not get mixed up. The feed line has the filter sock over the tank end of it, after all. Perhaps they just didn't want people to be able to mix up the lines?

Whatever you use, just make sure that you can get a good tigh junction between the hoses and the hard lines. If you're using metal lines, a "bubble" flare on the end would be a nice thing to have. (See the ends of the stock fuel rails for what I mean.)

--DD