super A zenith carb

Farmall Super A, AV, 100, 130, & 140 1939 - 1973

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Farmcub31
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super A zenith carb

Postby Farmcub31 » Fri Oct 28, 2016 6:01 pm

Hey guys I am new to the zenith carb on the farmall A and am needing some help. I just rebuilt the carb and installed a new float, I turned it over and measured the float to make sure I had the float height set 1 5/32 which I did. I can't get it started now and fuel keeps leaking out for some reason, its like my float is not seating. I now have it set at 1 10/32 and its still leaking whats up? I have a new rebuild kit and float in the carb. Am I right in thinking the higher the float the lower the fuel level should be in the bowl? What are some ways to get this carb figured out? Also I see lots of pics of an adjustable main jet on the zenith carb but mine is not adjustable with a needle, there is just the main jet and then an outer plug. Please give me some help on how I can get this going again and stop fuel from leaking out when I turn over the engine. Thanks guys.

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EZ
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Re: super A zenith carb

Postby EZ » Sat Oct 29, 2016 7:52 am

FC31,
A good day to you sir.
So where exactly is your carb leaking from?
When the float rises, it should push the needle up onto the seat and stop flow.
Just Do It !

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EZ
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Re: super A zenith carb

Postby EZ » Sat Oct 29, 2016 7:58 am

Maybe your float is working but you have a bad gasket or something like that.
I usually do a preliminary test (with the carb in my hand) where I turn the carb upside down so the float drops, then blow my own air into the fuel inlet. If you can't get any air in......you are golden.
Just Do It !

Farmcub31
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Re: super A zenith carb

Postby Farmcub31 » Sat Oct 29, 2016 7:59 am

its just leaking out the intake tube. Other then the float stoping fuel is there any place besides the needle and seat that fuel can leak out? Also is it normal to have a fixed main jet no issues there? When I hook up there carb and turn on the gas everything is fine no leaking. As soon as I crank it and try to start it after that it starts leaking.

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EZ
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Re: super A zenith carb

Postby EZ » Sat Oct 29, 2016 8:04 am

So is the tractor getting fuel?
Sounds like you have a bad connection at the carb intake.
Steel line?
Just Do It !

Farmcub31
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Re: super A zenith carb

Postby Farmcub31 » Sat Oct 29, 2016 9:04 am

O its getting tons of fuel. Its a rubber line going to copper. There is fuel early entering the carb its right when I turn the tractor over to try and start it that it starts leaking out the carb pipe going to the air intake. I see it weeping out the hole. I have all new gaskets and parts including a new float.

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Re: super A zenith carb

Postby staninlowerAL » Sat Oct 29, 2016 9:48 am

What's the history of this tractor? Last running? Compression check? Seems like the fuel is not being adequately pulled into the cylinders on the intake stroke. Have you tried to turn on the fuel, fill the carb then turn the fuel off, start the engine and turn the fuel back on? If you try this, there should be adequate fuel in the carb to start the engine and run for a couple of minutes. I don't know how the Cub Zenith carb compares to the A/SA Zenith carb but you could search the Cub Forum for Zenith carb info. I have some Cub Zenith carb info in pdf format, if you would like the file, send me an email address via PM and I'll email it to you. Stan

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Re: super A zenith carb

Postby Jim Becker » Sat Oct 29, 2016 11:43 am

If gas only "leaks" out of the carb after unsuccessfully trying to start the engine, you don't have a leaking carb. If the carb was leaking, fuel would run out with the gas turned on without trying to start it. You are sucking a bunch of fuel through the carburetor while trying to start. When you quit cranking, the fuel is draining back into the carburetor. You are probably over choking it and probably flooding it in the process. Your original float height was probably correct and is now wrong. Most Super A carburetors did not have an adjustable main jet, only those with the distillate or kerosene options.

You haven't actually said whether you can get the engine to start or not. I assume not. Check you ignition system. Make sure you have good spark and that the timing in right. Use less choke and more throttle.

Farmcub31
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Joined: Fri May 08, 2015 11:06 am
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Re: super A zenith carb

Postby Farmcub31 » Sat Oct 29, 2016 6:04 pm

I have fiddled with it with different setting and I did get it to start a time or to. So the higher the float is the quicker it will shut off fuel correct? I mean higher then 1- 5/32? so is that the measurement from the highest point of the float down to the carb body? I verified the float is shutting off and thats all fine. So measure from the base where the gasket sits up to the top portion of the highest point of the float thats 1- 5/32? just checking again. I don't know whats up brand new fun rebuild and its not working right. I was mowing a super bumpy area and after that started mowing another area. I started noticing the tractor did not have the full power it had before I started like it was starving for fuel. I ended up getting a rebuild just to make sure my carb was good to go, I also have a new float but now I can't get it going for anything. Thats where I am so far. So anywhere close to that float measurement it should run correct? and the smaller the measurement off 1-5/32 the more fuel will flow?


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