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Leaking fuel bowl on '73

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Dual 32mm 900 concentrics.

Fuel bowl leak on RH side.

Few lessons learned in case they are any use:

Problem traced to the brass float bowl seat. Use a small bolt underneath to tap it out. If it it slips through the hole and touches the seat face its toast. Not sure if was bad to start with but sure finished up that way.

Replacement ref: 622/121 from Burlen and £4.27 bargain except they currently have a 4 week lead time for manufacture. No-one else seems to stock them so its £32.00 for a whole new float bowl.

I stripped out both bowls and checked fuel height (not float height) following Greg Marshes site and measurements. Made up a feed for the fuel bowl with the old carb banjo with one end blocked off with a bolt. Scribed a line on bowl needle side. Couldn't figure out how to read at the end of the float. Greggs measurement is .21" from bowl surface. With a bit of juggling of needles between seats I got to about .25" or so. Level should be a tad higher but topped there. Fear of further leaking kept it conservative. To go further you also need the new adjustable floats or start tapping out the seats. Bushman site is really good too. Wish I had checked it out earlier.

When you start pulling off fuel lines (for me) everything starts to leak so my new friends are Dowty Washers. 3/8"/1/8" BSP for the banjo bolts to the float bowls and 1/2"/1/4" BSP for the bowl drain plugs. Had to re-use the old plastic bowl plugs as the 1/4" washers are too tight for the shiny brass ones. Now you can go ahead and tear down and tighten these parts at will without going through 20 fibre washers. £2.50 for 10 from RGM.

On the same subject, treated myself to stainless dual fuel line to replace the plastic and rubber one. Much better. £33 from RGM. Looks great.

I still have the new stay-up float and needle kit in case/when I hit the problem again. I like the fact that the float pivot is metal so no give when shutting the needle verses the plastic one. Owners club were cheapest for gasket kits at £2 each but for £17.50 you only get the stay-up float from the club whereas RGM give you the float + needle for the same price.

Cheers

Eddie

 

 

 

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On the same subject, treated myself to stainless dual fuel line to replace the plastic and rubber one. Much better. £33 from RGM.

 

Hopefully its now made from ethanol proof tubing but I bought one of these 10 years ago and then a few years later turned the petrol on after a winter layoff and the rubber pipe inside the stainless was like a sieve with petrol oozing out the full length. So I now make my own and use Tygon ethanol proof tubing. It does look good and is accurately sized.

 


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