HERE'S AN UPDATETHE OBJECTIVE: To fit replacement fuel filler hoses on my 1990 3.9 litre Plus 8.
THE PROBLEM: Finding a hose stiff enough not to flatten at the 45 degnree bend yet flexible enough for it to bend through 45 degrees (and more) to get each end onto the oulet below the fuel filler cap and the inlet on top of the fuel tank. The vertical space between these two tubes is probably about 6 inches or less.
HOSE TYPES: Thus far, I have ordered two 0.5 metre lengths of 51mm inside diameter fuel-resistant hoses. First, the wire reinforced type was far too stiff to bend whilst attaching it to the two connector tubes in the limited space available. Second I bought a length of plain cotton-reinforced rubber hose that was so flexible it flattened where it went through the 45 degree bend between the filler cap and the tank.
THE 45 DEGREE BENDThe following adaptions were made to the soft rubber hose.
Stiffening Spring - I tried using a home-made spring (as suggested by BILIBIB) that I made using 16swg stainless steel wire. I tried this spring fitted around the outside of the hose and also down the inside of the hose. The spring was very difficult to produce and did not improve matters overall. From the photos provided by BILIBIB, it seems his hoses are much longer than my own (which measure about 240mm long from end to end around the outside of the 45 degree bend).
Internal Bent Tube - I sourced on eBay, a very short piece of 2 inch O/D stainless steel tube comprising just a 45 degree bend
eBay 45 degree stainless steel pipe. I pushed this down the inside of the hose to the position where it was to bend through 45 degrees. The idea was that this steel tube would act as a mandrel inside the rubber and prevent it from flattening. This didn't work either; the hose just bent immediately next to it! This is because bending a straight piece of hose through a 45 degree bend involves the rubber compressing on the inside of the bend and expanding around the outside of the bend. Clearly, even cotton reinforcement provides little maleability within the rubber. If it didn't, the hose would fall off its end connections.
CONCLUSIONS - My sole conclusion is that the only fuel filler hose likely to work is a piece MANUFACTURED with a 45 degree bend in it.
MY LATEST ACTIONS - I Googled for a fuel filler hose including a 45 degree bend and ignored the genuine Morgan hoses whose prices suggest that somebody is having a laugh at we owners regarding pricing. The first I found was a rubber fuel filler hose offered by MERLINMOTORSPORT.CO.UK
Merlin Motorsport Fuel Filler Hose reasonably priced at £31.74 plus delivery and who later confirmed that its overall length was 10 inches (255mm).
Whilst Merlin answered my question, I found another hose offered by AUTOSILICONEHOSES.COM
Autosiliconehoses Fuel Filler Hose that was even more reasonably priced at £27.34 (with free delivery if ordering two pieces). This hose was fuel proof thanks to its 'Fluoro Liner' and more than adequate in overall length. So keen was I to end this harrowing saga, I had ordered two silicon hoses even before Merlin had confirmed the length of their own hose.
So now I wait with baited breath. Will this silicon hose prove as easy to fit as I had imagined at the outset?
