I have just made a new fuel pipe which joins both tanks .Made from Bundy tube as I could not get 5/16 copper. I have decided to double tape the pipe in the battery area using normal electrical tape, I don't like a fuel pipe so close to the battery. I have worked on American cars and some have rubber fuel lines impervious to petrol. Very strange that BMC never did this. The system also makes it difficult to fit the braided hoses. Anyone know why they used the Bundy tube ?
Allen BMC non expert. Thanks gotto g for the pics you need 1.2 metres of tube

Mine was a real pain to fit! If I ever need to remove the tanks it'll all be replaced with some new rubber hose and a T-piece

I split open a couple of lengths of heater hose to protect the metal connecting pipe from damage and the battery.

_________________

I used Dayco USA fuel hose and a brass tee piece. After 10 years I took the hose off and it was still like new. Soft and flexible, no swelling. I replaced it anyway with the same stuff. It is fine with unleaded, probably E10 too.
Edit:
I use a battery with the terminals to the left, away from the tank...

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I'm the same as Doc. Battery terminals away from the tank. I had enough slack in the cable to reach the battery.
Terminals to the right, inches away from the tank scared me...

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

Also the braided hoses were 1/4 inch which I bought from KC and pipe and SU pump has 5/16 both ends , I hope the 5/16 will tighten on the main fuel line which is 1/4 inch. Another day wasted trying to keep the car original. Next car will be a Cortina GT they are good to work on. I will now use just rubber fuel lines keeping them away from the battery.
Allen bad day at the shed.

Had similar issues.
See:
viewtopic.php?f=2&t=96998

When I realised the difference in diameter for the tank fittings, I bought a bulk length of 5/16 braided hose from UK, with end-fittings to neaten the finish. SU pump spouts are an in-between size for 1/4 and 5/16 inch so you can fit 5/16 hose from the tanks and 1/4 hose out to the main supply pipe. Ends up looking very original.