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Float Needle not holding on 1927 KIssel with Schebler Model S Carb


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Hi,  I keep getting an overfill on my updraft Schebler Model S carb- even after cleaning and filtering the gas.  I had a rotary 6VDC Carter pump and dial type regular and was measuring about 3-4 psi at the carb.  This even with the regulator dialed to 1 psi.  Thinking this was too much for the float needle to hold, I changed to 12 VDC Carter rotary which when running on the system 6VDC, puts out about 0.8psi.  This seems to be close to the theoretical vacuum pump head pressure [gravity at 1.5 foot above].  That pressure is about 0.92 psi.  I put it all together today and got the same overflow.  I think I must get a new viton tipped needle or something.  Does anyone have suggestions to get this fixed.  I'll gladly pay any good carb guy that works on these or can supply the part or customize the needle.  Thx in advance.  Doug

 

Float assy for Schebler Model S _1.JPG

Float assy for Schebler Model S _4.JPG

Edited by DBKissel
missed a word (see edit history)
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How heavy is the float?  I'd expect somewhere around 5/8ths Oz, that one looks heavier but not probably shouldn't be more than 3/4 Oz, if it weights more than that the fuel won't be able to lift it enough to close the needle valve.  The float also looks 'tipped up' in relation to the needle, try to bend the needle end down a whisker, I'd be making it 90deg to the float and try it, if no improvement give it a little more 'positive' bend and try that.  

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The play is 0.096 " as measured with a dial caliper.  The needle pivots under the retaining screw cap and when in position, and float is up, the float seems to be level in the bowl.

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Kinda looks like you can fill it without the top on and see what it isn't doing right.   The fuel comes in from below the needle valve, right? You have an electric pump and rig it up with your parts washer tank & fluid, a small screen over the top of the tank to set the carb on and test away.

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You might try a bit of valve lapping compound and lap the fuel needle and the seat GENTLY to remove any varnish, burr, corrosion, etc.; then wash both components in gasoline. If this does not work, then you might put in a new fuel valve and seat.

 

As far as a neoprene tip, I have not figured out how to incorporate a neoprene tip on this design because of the leading position pin required to center the tip in the seat.

 

The carb should NOT leak while running, but may when the engine is shut off.

 

Jon.

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21 minutes ago, carbking said:

 

The carb should NOT leak while running, but may when the engine is shut off.

 

Jon.

Correct !!!   A lot of cars have shut off valves to stop flow from vacuum tank to carb - ie the valves leaked when parked when the cars were new.  And, if you are no longer using a vacuum tank, then I would bet a pound of fuel pump pressure from an electric pump may even be a challenge. 

 

Best you can probably do is try value lapping compound followed by perhaps toothpaste or polishing compound. 

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I have done two Schebler carbs this summer with this needle.

I would lap the needle and seat with very fine grinding compound, clean thoroughly, assemble and check.

I would never attempt to run this carb with a electric fuel pump.

Vacuum tank or gravity feed only.

Dennis

 

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Dennis is correct.......it's only made to hole back the head on a vacuum tank, which is about 0 pounds pressure. Electric pumps on such a carb are a HUGE FIRE RISK and should not be done for any reason.

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Doug,

    My Driver Kissels are all sixes with Stromberg carbs but Here are my suggestions;

1. I’ve always had problems with fuel pumps - I only use the original vacuumed tanks and problems have gone away.

2. they all leak gas when parked for a long time. A shutoff valve installed under the tank reduces the leakage.

3. I’ve always rebuilt the carbs with NEW gaskets and needles. You can buy a kit for your Schebler. That way you don’t have to worry about rebending your old needle.

    Take care. Ron

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Thx to all for suggestions.  The fuel does not overflow all the time.  It seems to happen randomly on startup.  Another time it happens is when the car has run for 30+ minutes and then is stopped.  Start it up 5 minutes later and it might overflow.  I really like the idea of testing it with the car fuel pump.  I can make a tube to fill it off the car and observe with top off and try to reproduce the issue.  Maybe rotating the needle [which has a very very slight ridge on one side will do it.]  Then the problem is easier to solve. 

I'm big on getting a new seat and needle valve and hope Ron can supply a source.

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7 hours ago, Ozstatman said:
11 hours ago, Tinindian said:

Why not ask "carbking".

Jon already replied!

No, Jon did not reply to the question about a kit.  His reply was earlier.

 

On 9/8/2020 at 11:14 AM, carbking said:

You might try a bit of valve lapping compound and lap the fuel needle and the seat GENTLY to remove any varnish, burr, corrosion, etc.; then wash both components in gasoline. If this does not work, then you might put in a new fuel valve and seat.

 

As far as a neoprene tip, I have not figured out how to incorporate a neoprene tip on this design because of the leading position pin required to center the tip in the seat.

 

The carb should NOT leak while running, but may when the engine is shut off.

Does nobody read these threads from start to finish.  It certainly was easier when these posts were numbered.

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1 hour ago, Tinindian said:

No, Jon did not reply to the question about a kit.  His reply was earlier.

 

Does nobody read these threads from start to finish.  It certainly was easier when these posts were numbered.

I stand corrected. 😪

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I think we make kits for all 460 different Schebler model S carburetors.

 

Like the Marvel they later married, very little is interchangeable from model to model, so finding the carburetor identification number is crucial to acquiring the correct kit.

 

For single barrel carbs, the identification number is STAMPED approximately midway from top to bottom horizontally in a "boss" on the end of the carburetor OPPOSITE  the air valve.

 

For duplex (2-barrel) carbs the number is STAMPED over the "hump" in the top casting that houses the intermediate shaft.

 

THE IDENTIFICATION NUMBER IS ALWAYS IN THE FORMAT "SX-nnn" where nnn is a one, two, or three digit number from 1 to 460.

 

An example I remember SX-389 is the duplex used on the Duesenberg J. Another one often seen is the SX-7, which was a universal replacement carb, although why anyone would wish to put a Schebler S on something it did not come on is beyond comprehension!

 

THE CAST (RAISED) SV NUMBERS ARE TOTALLY MEANINGLESS!

 

Jon

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