<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Hank,<div><br></div><div>If I read your post correctly, the fuel is coming out of the jet in the carburetor into the intake manifold and then out the drain tube. Not from the overflow tube on the float chamber. I’ll proceed with this assumption.</div><div><br></div><div>The level of fuel at the jet is the same level as that in the float chamber. That is the way these SU carbs are designed. That is why float level is so important. If fuel is flowing out of the jet before the needle valve shuts off the fuel supply at the float chamber then your float level is set too high. You need to close the float needle valve with the float at a lower level. Instead of using 7/16th as a guide, try 1/2” and see if that stops the flow. But then you said you tried different settings. </div><div><br></div><div>Is there an obstruction that is preventing the float from rising all the way to the top to close the needle valve? Try a different float. Polish the post. Is there any wear in the fork or pivot in the casting that is not allowing the needle to move feely into it’s seat. I think that’s where the problem is. </div><div><br id="lineBreakAtBeginningOfMessage"><div>
<div>Richard Mayor</div><div>boyracer466@gmail.com</div><div><br></div><br class="Apple-interchange-newline">
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<div><br><blockquote type="cite"><div>On Dec 22, 2024, at 12:28 PM, Hank Leach via Healeys <healeys@autox.team.net> wrote:</div><br class="Apple-interchange-newline"><div><div>
<div> I have chased the cause of too much fuel exiting from the rear carburetor overflow of my 100 for years. These are H4 carbs-very simple design, but must be done correctly to perform. So I find that the jet is out of center and piston is sticking up above the flat about 1/8"-that would allow fuel to run into throttle area and out overflow drain tube.
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<div>No way to center jet on car. Remove carburetor-a 4 hour job- and clean and replace gaskets and gland washers-yes cork- and reassemble and center jet...now works perfect. Re mount carburetor and connect fuel lines-another 4 hour job. Both carb pistons drop with a clunk at the same time. Turn on key- fuel pump clicking-overflow again leaking. </div>
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<div>I have reset the floats and float needles (brass) were replaced many times-that's not the issue. No fuel in float bodies-they are not leaking. I just cant believe its too much fuel pressure but then again, this is a British Car. </div>
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<div>Float is brass but when shaked it is dry. I filled the float lid with carb cleaner while holding needle valve closed and no leaking. That's two places checked (these are unfortunately "new" parts) Now the next leak could be between the needle and jet if not closed off-also new parts-jet .090. Needles are QW as specified but i also have a set of ATs which are lean that I am tempted to try. Actually both needles are about the same at top .089, but ATs are a bit fatter at mid range. Problem is all testing stinks up the garage and creates an explosive atmosphere so best done outside in the rain.</div>
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<div>I know some folks like Grosse Jets-but I don't-- I prefer the simple brass ones with viton tips which do work if pressure is applied by forked leg-also new, and set to 7/16" or MORE. With covers off, both bowls are equally about 1/2 filled. Fuel pressure is a thought as it can push by the stops but its the correct pump and when key on clicks fast then slows to a stop... but then tick, tick which it should not do! Fuel is going out and down the drain tube to my swimming pool drip pan. Im tempted to measure the top of the needles to see if they are really at .089. Can't measure the new jet but its stamped "9" Maybe stick in a number drill to see if its round? Mind you, these carbs have about 125 miles total on them. As far as I know these are "genuine SU" parts-not Moss India knockoffs.</div>
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<div>I really thought that the centering was the issue and took the carb off for that reason which cured the drop-each drops equally with thud. That's not the problem. Any suggestions? Someone says use plastic floats...Hank</div>
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