Fuel Tank to Fuel Line

[kcrossle]

Coming off the the bottom of fuel tank there is a banjo bolt and then a stub of a threaded pipe which I assume originally had some sort of compatible female coupling to the fuel line to the carburettor.

Now, mating that to a swirl pot before a pump for fuel injection (Spyder Zetec), I'm looking to have a good junction, from the tank, for the fuel line. Which means connecting to the original threaded coupling off the fuel tank somehow. What size / thread is that coming off the fuel tank? It is *somewhere* about a 3/8" fine thread... but not exactly.

Not good to be inexact! Before I toss it all away and adapt something else, can anyone advise exactly what the size / thread is?

THANKS

Keith

[iain.hamlton]

Hi, Keith.

If there are bits in the fuel tank (paint, rust etc...), they can get stuck in the banjo bolt, reducing the flow. I replaced mine with a straight connection. The thread is 1/4 " BSP - I think. It is the same as the fitting for a British gas fire. Not sure if you can find anything to fit in America.

best regards, iain

[andyhodg]

Hi Keith

It is most likely a BSP (British Standard Pipe) thread. In the US there is a close but no match similar thread NP (National Pipe) thread. In my experience true BSP is difficult to source in the USA. What would you want to adapt to? You should be able to fide a UK web site that would send you the appropriate fitting. They are only small so should not cost much to ship.

Good luck

Andy

[CBUEB1771]

BSPP fittings are actually easy to find in the US. Dave Bean Engineering, Pegasus Auto Racing Supplies and others have a variety of BSPP fittings. Googling on "BSPP fittings" with turn up many other suppliers in the US and Canada. Parker manufactures many BSPP fittings in the US. If the banjo male thread that accepts the gland nut and olive actually measures 3/8" OD then it is 1/8 BSPP (0.383" OD X 28 TPI), 1/4 BSPP is 0.518" by 19 TPI. Remember that the BSPP threadform has a 55 degree included angle on the threads as opposed to the 60 degree standard for SAE threadforms.

[kcrossle]

Thanks for the comments - all very helpful with this intense and continuing learning experience that is my Lotus.

I had put the tank back in but pulled it to work on this. What I need to do, I think, is replace the banjo with one as in the picture (but larger). This will feed the swirl pot with a similar (larger fuel line) barb.

Make sense?

[CBUEB1771]

Keith,
There are many ways to adapt to your swirl pot inlet. You can replace the complete banjo bolt and fitting with an adapter. Parker makes straight adapters to go from male BSPP to female NPT. You will need to measure the threads on the banjo bolt first. I think the fitting in the bottom of the tank is 1/4 BSPP. Parker's 1/4 BSPP male to 1/4 NPTF is part number 1/4 X 1/4 F4OHG. They make similar adapters for 1/8 BSPP ranging to 1 BSPP. You can buy these online from Hydraulic House (http://www.hydraulichouse.com). Then you can screw whatever hose barb you need into the Parker adapter. The only problem here is the amount of vertical room you have below the tank to stack fittings. Another approach is to retain the banjo bolt and machine your own banjo fitting with a female NPT port on the side. I think the banjo bolt is only long enough to support a banjo with a 1/8 NPTF port. This approach eliminates any problems with vertical clearance under the tank.