Super A carb

Jay Poole · Feb 25, 2010

I have a 48 SA that has a Zenith 12911 carb on it. It came to me with a spring on the the carb side hooked to the governer link and run back and hooked on the air cleaner. I haven't gone into the engin but from all I can see it's a stock motor. This winter I replaced the intake Manafold, rebuilt the carb, tune-up that sort of thing and decided that I was going to get it back to stock. I set the throttle link as out-lined in the service manual and started her up... she only runs at wide open throttle... but the throttle plate is completely closed. I took the carb back apart and didn't see anything wrong, correct me if I'm wrong but isn't the the governer working and doing what it should, or is that where I should be looking. The service manual calls for a 10514 carb on this tractor but all I see says that the 12911 is a replacement for it. Thanks for any help.

Jonathan Mirgon · Feb 25, 2010

is the throttle plate all the way closed when the tractor is not running , or all the way closed when running ? It should not be running wide open if the throttle plate is closed when running. It's been a while since I fooled with one of those but I believe that the throttle plate should be full open when not running, Then after the tractor starts the governer pulls the plate towards the closed side to allow for idle speed. sounds like a governoe or linkage problem that was pre existing, especially if someone was using a spring to hold the plate closed as mentioned.

CNKS · Feb 25, 2010

One of my C's has a spring also -- haven't messed with it as yet. It is a governor problem, I assume linkage. All the 113/123 Zeinth carbs are similar. Very doubtful it is a carb problem, provided it is adjusted to specs, which for that carb is mainly the float, unless it has a main jet adjustment, most don't.

Farmer_Adam · Feb 25, 2010

I have a 1949 Super A that when I got it it would run full throttle after I would start it. It ended up being the thrust bearing in the governor. The small ball bearings inbetween the two metal disks were gone. The new thrust bearing isn't that cheap. I think it cost me around 20 dollars at a case ih dealership but it fixed the problem. Check the Case IH parts website to find out which part is the thrust bearing and to make sure that you aren't missing anything.

teddy52food · Feb 25, 2010

You must be mistaken. If the throttle plate is closed, the engine is at idle. There is a spring in the gov to open the throttle. Get rid of the spring on the linkage. The flyweights will close the throttle as the speed comes up. Get the governor off & if you don't know how to repair it, find someone that does.

Super A carb

Jay Poole

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Jonathan Mirgon

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CNKS

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Farmer_Adam

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teddy52food

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