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Embarrassing Question: Where the #^$%@ is the “Idle Air Bleed Channel Lead Ball”?


Professor

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 Good Morning,

 

I have a completely embarrassing question.  I have two Stromberg EXV-3 carburetors, one that came on my 1936 Chrysler Airstream C-8 (8 cylinder L-Head) and one that I ordered as a spare.  I also have a carburetor rebuild kit from Andy Bernbaum Auto Parts.  In the rebuild kit, there is a small round check ball called the “Idle Air Bleed Channel Lead Ball”.  

 

The carburetor parts list references this lead ball, but in taking apart both of my carburetors, there is no lead ball to be found.  Every carburetor I have ever rebuilt contains a check ball, but I will be darned if I can find it in either of the carburetors I have taken apart.  I have searched the web far and wide for a exploded view of my Stromberg carburetor, only to come up completely empty handed.

 

Recognizing that some carburetor rebuild kits are generic and may contain “additional” parts, I understand that it is possible that there is no check ball in this carburetor.  This said, there is no way I want to install my rebuilt carburetor back on the Chrysler and find out that there really IS a check ball somewhere in this carburetor, and I missed it.

 

Any guidance would be much appreciated.

 

Warm Regards,

 

Joe

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Stromberg used lead balls as plugs to seal access passages in the castings.

 

If you do not need to remove the old plug for cleaning the passage, just ignore it.

 

And item 26 in the picture is a check valve, which is a brass threaded fitting with an encapsulated steel ball.

 

We include the passage balls in most of the Stromberg kits, because the balls cost us about 4 cents each, and postage, in the rare case someone actually needs one, is $12.

 

Simply cheaper to include them.

 

The vendor should have explained this to you when you contacted the vendor.

 

Jon.

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Thanks so much for that image... it helps a GREAT deal.  It appears to me that the check valve (part 26) does not have a replaceable ball, but rather, it is part of an assembly.  I have the assembly (which looks like it has a Schrader valve on top) labeled as part 26, so I suspect I do not need to worry about a standalone check ball.

 

Now that this is resolved, I have another issue that arises.  At idle, I am getting WAY too much fuel delivered.  So much that the air/fuel mixture screw (Idle Needle Valve, part number 25) does not impact anything.  When the idle needle valve is screwed all the way in or all the way out, the idle speed does not change at all.  This is true for BOTH of the carburetors I have... the rebuilt carburetor and the original (as of yet) un-rebuilt carburetor.

 

I am hopeful that the issue is simply one of fuel pressure regulation.  I have installed a low pressure 6V electric fuel pump (6psi max) without a pressure regulator.  Perhaps even at 6psi, fuel is pushing past the float needle valve.  This would explain why both carburetors act the same. I ordered an adjustable pressure regulator and will regulate down the electric pump as soon as the regulator and fuel pressure gauge arrive.

 

I disabled the mechanical fuel pump by removing the outlet valve.  I will put the valve back in and try running the rebuilt mechanical pump to see if it corrects the problem.

 

Joe

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Enabled the mechanical pump and now, the the idle mixture screw has a small impact.  Screwing the needle all the way down (not tight) causes a slight, but noticeable, decrease in idle speed.  Screwing out the needle by 1/2 turn gives highest idle speed.  The engine will still not die with the idle mixture screw all the way in,

 

Speaking of idle speed, the engine wants to idle best at about 700 rpm, which seems a bit high from what I have read.

 

Finally, when running on the mechanical pump at about 30mph (temperature here is 86 F), I get vapor lock and have to turn on the electric fuel pump.  With the electric fuel pump on, I get low speed stumbling which smooths out with higher RPMs, exactly what I would expect if the electric fuel pump is pushing fuel past the carburetor inlet needle valve.

 

There doesn’t seem to be many PSI of margin between vapor lock and pushing fuel past the carburetor inlet needle valve.  Assuming the mechanical pump pushes 2psi (I am guessing here) and the electric fuel pump is at its maximum specification of 6psi, then I have about 4psi to play around with once the fuel pressure regulator arrives.

 

By the way, when I removed the cover over the mechanical fuel pump outlet valve, I could see the fuel boiling and pushing the output valve flap up to let the vapor out.  It was dancing around so much I had to let the engine cool down before I could install the outlet valve spring and cover.  With respect to the carburetor, with the engine off and hot, I removed the air filter and watched fuel dripping out of the venturi and instantly vaporizing into a small cloud of fuel in the carburetor throat.  Remembering that I have a vapor fuel filter (with a vapor line feeding back into the fuel tank) between the fuel pump and carburetor, I can only assume that the fuel in the carburetor bowl is boiling causing fuel to dump into the carburetor throat.

 

One final note: the Chrysler does not overheat at all according to the temperature gauge or an infrared heat measuring device, so I am relatively certain that abnormally high engine temperatures are not causing my vapor lock issues. Regardless, the pressure regulator should be in late next week and I will continue with the fine-tuning.

 

I would certainly welcome any comments thus far from the experts here. Hopefully I am troubleshooting in the right direction.

 

Joe

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Your shop manual should tell you that your carburetor wants 3 psi MAXIMUM!

 

More than that, and results are going to be less than desirable.

 

Yes, the carburetor CAN be modified (on the inside, by an expert) for a bit more pressure, but it is a tricky procedure and would require lots of time, effort, and parts.

 

As to a regulator, you want a regulator with an internal bypass, NOT the inline dial-type sold by the FLAPS in the $19.95~$39.95 (depending on the conscience of the seller). These are quite useful for those of us who garden, have a strong arm, and the typical rabbit problem in the garden.

 

Jon.

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Thanks Jon. I bought a Holly 12-804 on Amazon, but it has not shipped yet.  Do you have a recommendation? 
 

 

2 hours ago, carbking said:

Your shop manual should tell you that your carburetor wants 3 psi MAXIMUM!

 

More than that, and results are going to be less than desirable.

 

Yes, the carburetor CAN be modified (on the inside, by an expert) for a bit more pressure, but it is a tricky procedure and would require lots of time, effort, and parts.

 

As to a regulator, you want a regulator with an internal bypass, NOT the inline dial-type sold by the FLAPS in the $19.95~$39.95 (depending on the conscience of the seller). These are quite useful for those of us who garden, have a strong arm, and the typical rabbit problem in the garden.

 

Jon.

 

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My floor is covered with those little #^$%@  pieces that are usually found after you have bought a replacement part.🤔

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Joe......I have a bunch of these carbs up north, BXUV-3 which my books list as a correct replacement. We have much better core units, but this one was the easiest one to grab and get a picture of. You will need to change the linkage to fit your car. Price is 150 plus shipping. Carbking can comment if he thinks this is a good fit. Let me know. Ed

 

 IMG_4155.thumb.jpg.0ceb5591555b170f3318bdda7272240d.jpg

IMG_4154.jpg

IMG_4153.jpg

Edited by edinmass (see edit history)
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