Andrew Posted February 13, 2020 Report Share Posted February 13, 2020 Hi all I have aHerald 13/60 with a stromberg CD 150 carb. Had the carb overhauled four years ago by a professional place. On two occasions it is leaking fuel. I dismantled it did all the usual things tested the niddle valve by blowing through it and made sure the float cut the flow off. Made sure the floats were not punctured put it back together and all ok. But it has done it again. On my first trip out on a recent nice dry day. Any suggestions what the cause is and what to do to cure it. Thank you Link to comment Share on other sites More sharing options...
johny Posted February 13, 2020 Report Share Posted February 13, 2020 Hi, have you changed the fuel pump at all? An electric or replacement mechanical type have been known to produce extra pressure which can cause the needle valve to leak. Also how clean is your fuel system? There should be a gauze filter in the fuel pump that will show if much debris is coming from the fuel tank and which could then stop the needle valve closing properly. Also I believe theres been issues with certain replacement needle valves and perhaps a search on here would throw up some useful threads. Finally leaving the car for long periods can let the float chambers dry out through evaporation which can cause the float to stick and allow an overflow although this usually occurs on the first start up.... Link to comment Share on other sites More sharing options...
JumpingFrog Posted February 14, 2020 Report Share Posted February 14, 2020 Is it leaking or overflowing? 4 years is definitely enough time for the rubber o-ring that seals the jet holder to the float bowl to go hard. Very common place for leaks. Link to comment Share on other sites More sharing options...
johny Posted February 14, 2020 Report Share Posted February 14, 2020 Good call and it should be easy to tell which is happening as a float chamber overflow will come out of the small hole in the front face of the carb into the air filter housing where it drains out from the bottom.... Link to comment Share on other sites More sharing options...
dougbgt6 Posted February 14, 2020 Report Share Posted February 14, 2020 Could also be the dread rubber slivers jamming the valve open. They come off the inside of the rubber pipe and float about. Doug Link to comment Share on other sites More sharing options...
daverclasper Posted February 14, 2020 Report Share Posted February 14, 2020 I had some float valves that were flooding the carbs, though they appeared to seal when blowed through. The pump pressure is a lot higher than blowing. New valves cured it. Dave Link to comment Share on other sites More sharing options...
Pete Lewis Posted February 14, 2020 Report Share Posted February 14, 2020 yes where is the fuel leaking ??? from the front vent hole via the filter face or underside from the brass jet holder ???? most stromberg floats are solid dense foam so dont puncture or fill with fuel , unlike many SU small slivers of hose rubber are often the cause they get sliced off when refitting metal tubes into the various hoses and as doug says floatabout and jam in the back if the float valve agree many new pumps are too high pressure . 2.5psi is about the max they will accept. the underside jet holder has 0rings to seal the float bowl and smaller ones to seal the adjustable jet , often sold the wrong size and become early life leakers to check for slivers you best remove the carb and look inside the feed route , also pump a cupful into a jam jar see if any dive out the supply to the carb before you refit and remember every time you pull a hose the refit can make more of the little sods Pete Link to comment Share on other sites More sharing options...
daverclasper Posted February 14, 2020 Report Share Posted February 14, 2020 (edited) 25 minutes ago, Pete Lewis said: and remember every time you pull a hose the refit can make more of the little sods Never had that issue (yet?), though I have smoothed off any burs/sharper edges off the end of pipes. Also a smear of vaseline around the end of pipe and try to push hose on square and gently. Also, old hoses would be more prone to this, I assume Edited February 14, 2020 by daverclasper Link to comment Share on other sites More sharing options...
Colin Lindsay Posted February 14, 2020 Report Share Posted February 14, 2020 Me neither; it all depends on how you cut the hoses. Saw them you'll get lots of slivers; cut with heavy shears and they'll cut cleanly. I agree too that lubricating the end of the pipe saves damage when you're refitting. Link to comment Share on other sites More sharing options...
Iain T Posted February 14, 2020 Report Share Posted February 14, 2020 2 hours ago, Colin Lindsay said: lubricating the end of the pipe saves damage when you're refitting. Remind me what's the Topic and can you get the lube from the chemist??? Link to comment Share on other sites More sharing options...
Colin Lindsay Posted February 14, 2020 Report Share Posted February 14, 2020 No, I'll just point you in the direction of the bit that says: heavy shears. Link to comment Share on other sites More sharing options...
Iain T Posted February 14, 2020 Report Share Posted February 14, 2020 Ouch! A new meaning to measure twice cut once..... Link to comment Share on other sites More sharing options...
Pete Lewis Posted February 14, 2020 Report Share Posted February 14, 2020 there are loads of pipe and hose lopper's about but all we used on nylon air pipes to save any debris was one of these simple tools and over 20 years on still works a treat pete Link to comment Share on other sites More sharing options...
NonMember Posted February 14, 2020 Report Share Posted February 14, 2020 5 hours ago, Colin Lindsay said: it all depends on how you cut the hoses. And the pipes. I always use a proper pipe cutter - the type you tighten and spin round the pipe - to avoid jagged pipe ends. Then I use a very sharp scalpel to cut the hose - if it needs more than two swipes it's not sharp enough. Link to comment Share on other sites More sharing options...
Andrew Posted February 14, 2020 Author Report Share Posted February 14, 2020 Hi all answers to question. It is defiantly a overflow problem as when the car is at rest and as soon as engine switch off no petrol leaks start up and it leaks again at the back and into the air filter box. No I have not changed the fuel pump. I have just ordered a new valve from James paddocks so when I have fitted it I will let you all know the outcome. Thanks for all your suggestions and help Link to comment Share on other sites More sharing options...
Andrew Posted February 14, 2020 Author Report Share Posted February 14, 2020 Sorry guys also forgot to say I have a club shop fuel filter fitted before the pump Link to comment Share on other sites More sharing options...
Pete Lewis Posted February 15, 2020 Report Share Posted February 15, 2020 if the old needle valve has no foreign bodies the old trick to re seat was to give it a light tap with a small hammer , ( but not if it has a viton tip) and you cant strip out a strom needle to tell whats on the tip but its normally metal were as a dreaded SU it all falls apart on both there should be a thin sealing washer or fuel will pass in the threads. and if you dont want to upset the mixture settings you can remove the strom float bowl leaving the jet holder in place and note the float may have two valve arms and can be refitted upside down brilliant site for diy pictures of how to its TR but the basics remain with most of our cars https://www.buckeyetriumphs.org/carburetors Pete Link to comment Share on other sites More sharing options...
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