<p dir="ltr">My BN1 #724, engine number 139756, has no float bowl drain tubes, just the red notched washer and chrome vent at the top screw . I have never had the problems that you report. The floats are original. I cleaned and rebuilt with a Moss kit. If one of my carbs worked right and one did not, after replacing all rebuild able parts, I would replace the malfunctioning carb. If that fixes things you can explore the faulty carb at leisure. If it doesn't, then the rear carb wasn't the problem.<br>
-Roland </p>
<br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Mon, Dec 23, 2024, 1:19 PM Hank Leach via Healeys <<a href="mailto:healeys@autox.team.net">healeys@autox.team.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>Michael-that is why I asked the question in the beginning, Where is the fuel coming from and what is the cure for the problem? I agree that the fuel is "atomized" in the throttle area and that would be the best condition to send it to the engine but this car is dumping fuel and I cannot find the mechanism to stop that flow. Suggested lighter nitrile floats are at the top of the list, if in fact my brass ones are bum. Bill Lawrence modified his intakes possibly due to fuel issues? The system on this early car (same as yours) is a bit "cruder" than the revised float bowl vent system (with no manifold drain?). And, I cannot see anything wrong the float setting as presently set.</div>
<div>The fuel is not coming out the jet with the key off and the float bowls full to proper level-it is as you said below the top of the jet. Float valves are closed. Its when the key is on and fuel pressure is applied that I am getting the overflow condition. I was hoping that someone else on the team has had a similar experience. Hank<br>-------------------- <br><br>From: "Michael Salter" <<a href="mailto:michaelsalter@gmail.com" target="_blank" rel="noreferrer">michaelsalter@gmail.com</a>> <br>To: "Hank Leach" <<a href="mailto:gradea1@charter.net" target="_blank" rel="noreferrer">gradea1@charter.net</a>> <br>Cc: "Healey team" <<a href="mailto:healeys@autox.team.net" target="_blank" rel="noreferrer">healeys@autox.team.net</a>> <br>Sent: December 23, 2024 at 12:21 PM PST <br>Subject: Re: [Healeys] overflowing fuel into intake drain tube </div>
<div>
<div class="gmail_default" style="font-family:arial,sans-serif;font-size:small">Sorry Hank but I think you have that wrong.</div>
<div class="gmail_default" style="font-family:arial,sans-serif;font-size:small">In and SU carb,and for that matter almost every other type of carburettor, fuel DOES NOT pump out through the jet. </div>
<div class="gmail_default" style="font-family:arial,sans-serif;font-size:small">The fuel level, as mentioned previously, is controlled by the float chamber float valve to never actually be above the top of the jet. It is only the flow of air across the carburettor "bridge", where the jet is positioned, that draws fuel up through the jet to be atomized into the airflow and into the inlet manifold. </div>
<div class="gmail_default" style="font-family:arial,sans-serif;font-size:small">This is all related to <a href="https://www.google.com/search?client=firefox-b-d&q=Bernoulli%27s+principle" target="_blank" rel="noreferrer">Bernoulli's principle</a> which is the basis upon which all carburettors work.</div>
<div class="gmail_default" style="font-family:arial,sans-serif;font-size:small">If fuel is coming out of the jet when the engine is not running then the mechanism controlling the float level is not operating correctly.</div>
<div class="gmail_default" style="font-family:arial,sans-serif;font-size:small"> </div>
<div class="gmail_default" style="font-family:arial,sans-serif;font-size:small">M</div>
</div>
<div> </div>
<div class="gmail_quote">
<div class="gmail_attr">On Mon, Dec 23, 2024 at 1:37 PM Hank Leach via Healeys <<a href="mailto:healeys@autox.team.net" target="_blank" rel="noreferrer">healeys@autox.team.net</a>> wrote:</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>Ah! A rebel in the crowd. I looked at a bunch of photos of 1953 100 engines on the web. Many are configured as mine with NO FLOAT BOWL DRAIN TUBES. The <em>later </em>engine setups have drain tubes in the lid. This includes the cars using H6 carbs (Lemans). Also, on these early designs there is a different carb adaptor. Part 1B1672 which has a lower drain in the casing<span style="text-decoration:underline"> up to engine # 139915</span> (my engine 139563). Of course Moss, etc. only sell the later style products. but some books show the solid float lids and some show vented lids and some show a lid with a drain tube (air vent).</div>
<div> </div>
<div>So, in theory the way the early system works; fuel is inlet from the float chamber and enters the jet thru a hole in the tube positioned between the two gland washers which are to keep the fuel intact. when the choke is pulled that jet hole is lowered to send in, as the British say..."a neat petrol supply" to start the car.</div>
<div>Now, if you turn on the key, fuel pumps in and is moved thru the jet into the throttle area and into the manifold. <span style="text-decoration:underline">Unless the engine is now turning</span> and suction from the piston is active, the fuel will run haplessly in the intake manifold and out the drain tube to the ground. So the important procedure in these early systems is turn the key and crank the engine <span style="text-decoration:underline">immediately</span> or it will overflow fuel down the drain tube. I'm here testing the operation of the carburetors in a static mode-its not going to do anything but spew fuel to the ground. Right?</div>
<div> </div>
<div>The later design using a float bowl vent tube also send fuel into the manifold but without a drain tube the fuel will go into the engine, as the Moss PDF described, diluting the oil and washing the cylinders. Sounds like the best method of starting up is to crank the engine as soon as you hear the fuel pump click...I typically have waited until the pump stopped (float bowls full) before cranking. Live and learn?Hank</div>
<div> </div>
<div><br>-------------------- <br><br>From: "WILLIAM B LAWRENCE" <<a href="mailto:ynotink@msn.com" rel="noopener noreferrer" target="_blank">ynotink@msn.com</a>> <br>To: "Hank Leach via Healeys" <<a href="mailto:healeys@autox.team.net" rel="noopener noreferrer" target="_blank">healeys@autox.team.net</a>>, "Bob Haskell" <<a href="mailto:rchaskell@earthlink.net" rel="noopener noreferrer" target="_blank">rchaskell@earthlink.net</a>>, "richard mayor" <<a href="mailto:boyracer466@gmail.com" rel="noopener noreferrer" target="_blank">boyracer466@gmail.com</a>>, <<a href="mailto:gradea1@charter.net" rel="noopener noreferrer" target="_blank">gradea1@charter.net</a>> <br>Sent: December 22, 2024 at 9:29 PM PST <br>Subject: Re: [Healeys] overflowing fuel into intake drain tube</div>
<div style="font-family:inherit;font-size:inherit;color:inherit;background-color:transparent"> </div>
<div style="font-family:inherit;font-size:inherit;color:inherit;background-color:transparent">I’d like to be able to answer that, but I have to confess I’ve modified the induction system on mine (I know, I’m going to Hell) and I’m a little fuzzy on the details. If memory serves (a doubtful premise) the float bowls originally had an open vent arrangement on the top with no drain tubes. The car was built up from several dozen boxes of parts, so that may not have been correct. About 20 years ago I built a pair of H6s and installed those with drain tubes. The car is a bitsa anyway so originality is secondary, or maybe tertiary…</div>
<div style="font-family:inherit;font-size:inherit;color:inherit;background-color:transparent"> </div>
<div style="font-family:inherit;font-size:inherit;color:inherit;background-color:transparent">Bill Lawrence</div>
<div style="font-family:inherit;font-size:inherit;color:inherit;background-color:transparent">BN1 554</div>
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<div id="m_3659040959950062496m_-6618822986480632876divRplyFwdMsg"><strong>From:</strong> Healeys <<a href="mailto:healeys-bounces@autox.team.net" rel="noopener noreferrer" target="_blank">healeys-bounces@autox.team.net</a>> on behalf of Hank Leach via Healeys <<a href="mailto:healeys@autox.team.net" rel="noopener noreferrer" target="_blank">healeys@autox.team.net</a>><br><strong>Sent:</strong> Monday, December 23, 2024 1:59 AM<br><strong>To:</strong> Bob Haskell <<a href="mailto:rchaskell@earthlink.net" rel="noopener noreferrer" target="_blank">rchaskell@earthlink.net</a>>; richard mayor <<a href="mailto:boyracer466@gmail.com" rel="noopener noreferrer" target="_blank">boyracer466@gmail.com</a>><br><strong>Cc:</strong> healeys <<a href="mailto:healeys@autox.team.net" rel="noopener noreferrer" target="_blank">healeys@autox.team.net</a>><br><strong>Subject:</strong> Re: [Healeys] overflowing fuel into intake drain tube
<div> </div>
</div>
<div>
<div>Thanks Bob-yes the Moss site confirms they have alternate nitrile floats and about $20 each. Looking at the diagram there is a drawing of the float chamber overflow AUC1866 (451-250) $24.99 each. I do not have these overflows on my float bowls (as Richard Mayor mentioned their location) Instead the early cars have silver vent caps and a red washer which allows air out and those two intake manifold copper drain pipes at the bottom of the carb intakes. There is a PDF note on that part which reads:</div>
<div> </div>
<div>"These pipes are open to the atmosphere, for two reasons: first (and most important) they allow the fuel coming into the float bowl to displace the air in there so the fuel can reach its correct level in a timely manner. Second, if the float valve (needle-and-seat) should stick open (as they do when a bit of grit is trapped on the mating surfaces) the fuel will be piped out and down – away from the engine. If the <strong>fuel could not escape through the overflow pipe, it would pour down the carburetor throat into the engine</strong>. With that much liquid gasoline, not all of it will vaporize before the spark plug fires. The fuel that does vaporize will make the mixture so rich (as if the choke were engaged) the car will belch black smoke out the tailpipe. The engine will eventually flood and die."</div>
<div> </div>
<div>The point here is that not having those overflows on the float bowls; the overflow is actually after the throttle plates on my car. I wonder how Bill Lawrence's early car is configured and if he has float bowl overflows or intake overflows? Is it possible that this is a clue to my delima? Trapped air? Hank</div>
<div>-------------------- <br><br>From: "Bob Haskell" <<a href="mailto:rchaskell@earthlink.net" rel="noopener noreferrer" target="_blank">rchaskell@earthlink.net</a>> <br>To: <<a href="mailto:gradea1@charter.net" rel="noopener noreferrer" target="_blank">gradea1@charter.net</a>>, "richard mayor" <<a href="mailto:boyracer466@gmail.com" rel="noopener noreferrer" target="_blank">boyracer466@gmail.com</a>> <br>Cc: "healeys" <<a href="mailto:healeys@autox.team.net" rel="noopener noreferrer" target="_blank">healeys@autox.team.net</a>> <br>Sent: December 22, 2024 at 4:28 PM PST <br>Subject: Re: [Healeys] overflowing fuel into intake drain tube</div>
<p>Hank,</p>
<p>I think the newest floats are made from nitrile rubber - nitrophyl, not plastic. Supposedly unsinkable.</p>
<p>Cheers,</p>
<pre>Bob Haskell
Austin-Healey 3000 roadster registrar</pre>
<div>On 12/22/24 17:49, Hank Leach via Healeys wrote:</div>
<blockquote>
<div>I actually cannot figure where all the fuel is coming from. In static mode-key off and float bowls at proper level-with dashpot and piston removed, no fuel is apparent (as Michael says about 1/8" below jet or as you say equal to float setting). However, with key on and carbs together it's a different story-fuel is flowing steadily. The suggestion that was made that we really need to have clear plastic float bowls has merit. I cannot tell if the brass float is pushing hard enough to shut off the peg on the valve. When held shut by hand its positive.</div>
<div> </div>
<div>If the float is "heavy", then it will not effect enough pressure on the peg to stop the flow. This is why someone suggested plastic floats instead of brass. Fuel is the shut off mechanism. I have swapped float and needle valves from front to rear carb in hopes that the front one will now start leaking. That may be a clue to the issue. Waiting for a dry day (next year?) to test that theory.<br>-------------------- <br><br>From: "richard mayor" <a href="mailto:boyracer466@gmail.com" rel="noopener noreferrer" target="_blank"> <boyracer466@gmail.com></a> <br>To: "Leach Hank" <a href="mailto:gradea1@charter.net" rel="noopener noreferrer" target="_blank"> <gradea1@charter.net></a> <br>Cc: "healeys" <a href="mailto:healeys@autox.team.net" rel="noopener noreferrer" target="_blank"> <healeys@autox.team.net></a> <br>Sent: December 22, 2024 at 2:23 PM PST <br>Subject: Re: [Healeys] overflowing fuel into intake drain tube <br>Hank,</div>
<div> </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> </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> </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="m_3659040959950062496m_-6618822986480632876x_lineBreakAtBeginningOfMessage">
<div>
<div>Richard Mayor</div>
<div><a href="mailto:boyracer466@gmail.com" rel="noopener noreferrer" target="_blank">boyracer466@gmail.com</a></div>
<div> </div>
</div>
<div><br>
<blockquote>
<div>On Dec 22, 2024, at 12:28 PM, Hank Leach via Healeys <a href="mailto:healeys@autox.team.net" rel="noopener noreferrer" target="_blank"> <healeys@autox.team.net></a> wrote:</div>
<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.
<div> </div>
<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>
<div> </div>
<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>
</div>
<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>
<div> </div>
<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>
<div> </div>
<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>
</div>
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