GaryBudd

Carter BB-1 fuel leak

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Been awhile but started the 29'DeSoto K today.I now have gas leaking from bottom of carb. Doesn't appear to be stuck float.Could this be caused from my electric fuel pump? It is a low pressure 6 volt.If so can someone suggest a fuel pressure valve for me. I have enclosed a photo of my carb . At idle no leak but as I rev it up it leaks more.

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If it doesn't leak at an idle I don't think it is too much pressure.  With an electric pump the pressure is constant no matter the speed of the engine.  When the engine is rev'd up the pressure from the pump is the same so if you then have a leak it must be internal in the carb.

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Is it a constant leak once the revs go up?  These updraft carbs have a small opening at the bottom to allow accumulated gas to drain out when you shut the car off.  Is this where the gas is coming from?  Or, have you located the source of the leak?  You say the bottom, but can you tell where on the bottom?

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6 hours ago, Tinindian said:

If it doesn't leak at an idle I don't think it is too much pressure.  With an electric pump the pressure is constant no matter the speed of the engine.  When the engine is rev'd up the pressure from the pump is the same so if you then have a leak it must be internal in the carb.

Yes, agreed.

Also, if it was a high pressure issue, it would be leaking from the vent hole and/or the pump rod entry and out the main jet down the throat. 

 

But a pressure regulator would be a good idea. I use one of these;

 

http://www.ebay.com.au/itm/Speco-Meter-FUEL-PRESSURE-REGULATOR-1-6-PSI-512-00-AUS-WARRANTY-/131932272533

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Yesterday after car had not been started for 2 days with throttle closed no leaks,I pushed to full open and leak started again.I have enclosed a photo of spot where gas is coming from. I sent this carb out for rebuild and I am Leary of opening it up and causing more problems.Any ideas ? I have a low pressure fuel pump installed. Red arrow shows where gas is leaking.

DSCF2413.jpg

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two things cause my bb1 to leak underneath to much fuel by either closing the choke plate and kicking the accel pedal two many times,if you have the brass accelerator plunger it will throw a bunch of fuel up also the float set to high will flood it when mine is running there is no better then a BB1 but takes very little to throw it into the peeing flow mode, try no elec pump on, and no choke closed, just one pump and motor good luck this is just my experiences

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Perfectly normal for excess fuel to flow out from there when attempting to start.  I hope you don't have your exhaust passing under the carb. Not long ago the carbking explained that you can thread a pipe to feed back up the carb to feed the excess fuel.

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Here is Carbkings explanation, lot better than mine;

 

Quote

When the engine is turned off, with an updraft carburetor, all fuel currently in suspension in the intake manifold will fall (gravity) to the throttle plate, and then into the air intake of the carburetor. To counteract this issue, Carter offered a "drip tube". There is a threaded boss in the lowest point of the air intake with a tiny hole. All of the gasoline falling into the air intake will congregate just above the hole. The drip tube was a piece of copper tubing connected on one end to the threaded hole in the intake, then dropping a couple of inches, sometimes making a loop for more volume, and finally connecting to the threaded hole in question in the picture, which is above the throttle plate and exposed to engine vacuum. When the engine Is turned off, the fuel will accumulate in the drip tube. When the engine is started, the fuel in the drip tube is pulled into the intake, and acts as a "starter circuit" instead of the physical choke. Fuel leakage is not a desirable trait on a boat, and the drop tube pretty well solved the issue!

 

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7 hours ago, maok said:

Here is Carbkings explanation, lot better than mine;

 

 

My concern is the fact the exhaust does run under carb. If possible could someone post a photo of carbkings solution?

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Carbking's solution wold work  but where he attached tubing at the top of the carb mine is just a blank boss.I just don't have the nerve to try  drill and tap.

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The 289s has boss

the  517s has the boss's at top the bottom some has threads some don't but bottom cannot really damage anything just the top is tricky

the 517s is actuatly a coe truck chevy like 49-50 works very well once all rigged and looks just like the old 4a3's etc., 

good luck you can always take it off and take to a machine shop and ask them to drill and tap

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While removing the carb this morning I found anther spot where I might be able to apply Carbkings tubing solution.I have marked it with an arrow.Could this be used? I have to thank all that are working with me on this,I am a first timer with an antique car and I'm doing this alone.

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Yep, that's where carbking  recommends. Its a vacuum port that you can use to tune the carb as well. Same place as mine.

Edited by maok
errors (see edit history)
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I got the tubing run and it did indeed solve the problem.While I had it running I thought with it up on jack stands I should see if the cluch is ok.Throw out bearing is hung up on bits of a sleeve. The transmission is marked T2C-1.Where would I go to find replacement parts?The photo shows broken sleeve.

File.jpg

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If that sleeve is anything like the one I had in my 29 Plymouth, we got trouble right here in River City.  The piece fits on the front of the transmission over the input shaft and the throwout bearing slides on it.  Unfortunately, they are made out of some sort of pot metal that disintegrates over the years.  this is what it looks like on my 32 Dodge Brothers transmission...

 

IMG_2236.thumb.jpg.fa9910e98bc8880a41aa0c45053c0721.jpg

 

Luckily, Chrysler figured out the pot metal sleeve didn't hold up and mine is machined cast iron.

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Gary,

i have my 517s solid cast iton bottom what a B! To size and tap that cast iton steel it drilled fine but took all my strength to tap it or should i say get it started that parts done whew, 

In answer to next delema I think I have a spare tranny but I think its on your clutch housing side I am guessing from photos how far are you from hershey?

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Here is one of my BB1 517s Carter drilled and tapped to prevent dripping fuel from flooding a hot engine,the intake side right on the hot exhaust pipe hopefully preventing fire, Thanks for the suggestion!

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