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#1 carburettor leaking fuel

Posted: Mon Feb 18, 2019 4:37 pm
by Lemans88
After 31 years of moderate use a recent outbreak of misfiring under load seems to be traceable to fuel leaking from under the f/o/s Stromberg.

Before I set about closer inspection & dismantling on a nice warm day, can anyone please advise size of, & preferably a source for, the jet cover neoprene (?) O ring so I can at least replace that if it's the culprit?

Thanks.

#2 Re: carburettor leaking fuel

Posted: Mon Feb 18, 2019 4:42 pm
by JJC
Best source for correct part, and sage advice, is always Joe Curto in NYC, USA. In this day and age with email, cell phones, with satellite links, and quick shipping, he is the man !! Check his web page.

JJ

#3 Re: carburettor leaking fuel

Posted: Mon Feb 18, 2019 4:50 pm
by Heuer
In the UK: http://zenithcarb.co.uk/?SID=s9r9m67557 ... ore=zenith

Lots of information concerning overhaul and parts along with downloads of manuals and parts lists. We also have a few documents in the Forum Knowledge Base:

Stromberg Overhaul Guide (74 pages!): https://www.dropbox.com/s/clmwrlgonv8gx ... 2.pdf?dl=1
Stromberg manual (Leyland): https://www.dropbox.com/s/kd8urr3l411dh ... d.pdf?dl=1
Stromberg Needle guide: https://www.dropbox.com/s/domenkpzexkqw ... e.xls?dl=1
Stromberg Strip down by David Lacey: https://www.dropbox.com/s/48pmsd9osrrwi ... n.pdf?dl=1
Pictorial Stromberg strip down guide: http://www.howacarworks.com/fuel-system ... arburettor

#4 Re: carburettor leaking fuel

Posted: Mon Feb 18, 2019 11:11 pm
by rossco_j
Thanks for the links David. Very useful...

#5 Re: carburettor leaking fuel

Posted: Tue Feb 19, 2019 12:34 pm
by Ole-xke1974
I had similar fuel leaks from under my Strombergs.
That was after a refurbishment that off course included new needle valves. Guess what, one of the new valves started leaking after just a couple of years. No trace of crud in it, so I replaced it with an old one that has worked since.
An other time it was the plugs with the O-ring. Not the O-ring, but the plug was weak and brittle and could not stay tight and snug. SNG supplied the plugs in two days.
Cheers ...... Ole

#6 Re: carburettor leaking fuel

Posted: Tue Feb 19, 2019 11:12 pm
by 71 V12
I researched the dimension of the o ring a while ago and came up with this:

https://www.ebay.co.uk/itm/Imperial-O-R ... 1438.l2649

I have not fitted them yet but cheap and easy to fit, maybe worth a try.

#7 Re: carburettor leaking fuel

Posted: Tue Feb 19, 2019 11:32 pm
by vee12eman
One of the issues with the o ring seal under the carb is corrosion of the float chamber body. If this has occurred then new o rings may prove to be a short term fix. Once disturbed and cleaned (because you will clean it before refitting), the pitting from the corrosion may actually be worse than before, since the corrosion itself is gone, leaving only the pits. A new o ring may or may not cope with this for an indeterminate length of time.

I overcome this with a very thin smear of a FUEL RESISTANT sealant, making very sure none ends up inside the chamber bowl. My method is to apply to the the lowest inside portion of the bore so that as the bowl is refitted, the new seal tends to push the sealant down and out of the bore. I then apply a little more sealant around the plug, again, sparingly. I now do this routinely, even if I can’t see corrosion in the chamber bowl bore. As already suggested, I also replace the plastic plug completely (if applicable) as they tend to become weak and or brittle over time and frequently fail to retain correctly. You can change the chamber for a new one too, but it starts getting expensive and I can’t afford that!

Regards,

Simon.

#8 Re: carburettor leaking fuel

Posted: Wed Feb 20, 2019 12:36 pm
by Ole-xke1974
vee12eman wrote:
Tue Feb 19, 2019 11:32 pm
I overcome this with a very thin smear of a FUEL RESISTANT sealant, making very sure none ends up inside the chamber bowl. My method is to apply to the the lowest inside portion of the bore so that as the bowl is refitted, the new seal tends to push the sealant down and out of the bore. I then apply a little more sealant around the plug, again, sparingly. I now do this routinely, even if I can’t see corrosion in the chamber bowl bore.

Regards,

Simon.
Good tip, thanks Simon