Farmall Cub Forum -- Questions and answers to all of your Cub related issues.
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I have used your carb pages on the web and love them just wish I could print them so I could put them in my book. When I print them they turn out where I can not use them.
Anyway I have just rebuilt a carb for a "H" and I set the float level drop to 1-27/32" from the top. It doesn't give the 2 dimensions in my directions like yours gives. Anyway I need to figure it out becasue they say fuel level should be 7/8" and I checked it with your test procedure and I get 3/8" from the top. That is 1/2" to much fuel. I left it for now it seemed to run ok but it isn't smooth at high rpms and I can not seem to get it to be smooth. Will to much fuel cause this? What happens when there is to much fuel level and what happens when it is to low? I have to readjust it in my cub it is to low and the "H is to High"
Do you have any better carb float dimensions for the "H" other than the ones I got in my rebuild kit? again they gave me 1-27/32" (height of float from upper body) and 7/8" fuel level.
any help would be great.
Both conditions are hard on the engine and hurts performance.
Sorry, I do not have any carburetor info for the H but we can work with the info you have. You know how far the fuel should be from the top of the bowl and that is the most overlooked adjustment to making a carburetor perform properly. Get the fuel level as close to spec as you can, just as you would if setting the timing or adjusting the clutch.
I want to make sure we are both talking about the same things. Float height is the distance from the float to the casting when it closes the needle valve. Measure with the throttle casting upside down. You measure from the casting to a specific spot on the float - I don't know where on the float you measure with the H carb. But, you know you've got about 1/2" too much fuel in the bowl so all you need to do is increase the distance from the casting to the float by 1/2" - how you measure now is not very critical.
Float drop is how far the float hangs down from the throttle casting. Measure with the throttle casting rightside up.
Make sure your float floats - give it a gentle shake and listen for fuel sloshing. Rule out a leaking float.
Readjust the float height first. Bend the float arm until the float is 1/2" farther from the casting, that will reduce the fuel height in the bowl and get you closer to spec. It might take several trys to get it right - very worth the extra effort now to head off problems later on.
The float drop will not affect engine performance - it keeps the float from bumping against the bottom of the bowl. If you don't have that setting, estimate the drop by measuring the depth of the bowl and make sure the lowest part of the float drops about 3/8" or so less than the bowl depth.
Hook the carb up to a fuel source and measure the fuel height, readjust the float height up or down to get it right.
Hope this helps,
Just curious Carl, I haven't worked on a hole heapin bunch of carbs but most that I have seemed like after making float adjustment, float was almost dead level with top housing if unit were turned upside down. That is it would rest level on the needle valve and float body would be level with bottom of top housing. So I've kinda got the idea that if a feller didn't know setting but just made sure the float was as descibed it would be close. Am I all washed up or is there some merrit here? WK
1/2 inch is a long way off. I don't think it passes a reasonableness test. Make sure your float floats and make sure your measurement is reasonably accurate and you are working from the right specs. You would have to bend the bejesus out of a float to change it 1/2 inch.
Hi Carl, glad to see you're still Lurkin'
You said, "Float height is the distance from the float to the casting when it closes the needle valve. Measure with the throttle casting upside down. You measure from the casting to a specific spot on the float".
Is this from the bottom of the carb casting, on the inside
Looks like we need a 2nd opinion. Can anyone verify float adjustment specs for the H?
WK - Eyeballing an adjustment is a good starting point until you get the right numbers. It's best to get your information from the factory manuals, instructions in the kits can be misleading and have been known to be wrong. When you don't know the specs, rely on your good judgement and do the best you can with what you got.
Jim - You're right, 1/2" is a big difference. I've had to drop the float an additional 1/4" in a Cub carburetor to get the correct fuel level, 1/2" in a larger carburetor is not out of the question. Buckled pontoons, mangled arms and botched repairs can make a simple adjustment into a headache. Or there could be 2 gaskets under the needle cage.
Mike - For a Cub - Install the bowl gasket and measure from the edge of the throttle body to the very bottom of the float. Straighten out the warped casting first.
I think I messed it up and it would have been close if I left it. I bent the shit out of the float when I did the rebuild becasue in the picture in the rebuild instructions it showed the carb like it was hanging on the tracotr and then gave the dimension 1-27/32. So what I did is set the float drop to 1-27/32 instead of flipping the carb upside down and setting the float hieght to close the needle on the seat. I did notice now that in the picture on the directions it shows the carb hanging like it would on the tractor but it shows the float closing the needle valve and gives the 1-27/32 so it is most likely my mistake. I hope you are understanding what I am trying to say.
so let me get this straight float hreight is when the carb is upside down and you measure from the gasket to the top of the float (which is really the bottom) so from the gasket to the top of the float with the float resting on the needle will be my 1-27/32.
and you say float drop doesn't matter as long as it doesn't hit the bottom of the carb float bowl?
ok this is making lots of since I look back and I did it backwards and I was thinking damn I really have to bend the shit out of this float. If I would have checked it right I bet it would have been super close.
thanks I will let you know what I find out but wont be till this weekend.
At least now you have an idea of what went wrong. Adjusting the float back to the original setting is an easy fix, be careful not to damage the pontoons, break a float arm or soldered joints.
It's easy to get confused with up and down when you turn it up-side-down. I should have prefaced with something like "bottom of float = lowest part when installed on tractor" or some such thing. Some things are hard to put into words. That's why I like to use pictures, even then sometimes they don't show enough information.
Try to get the IH manuals for the H, you'll have better instructions and the factory specs. Now that stuff is being imported from all over the world, expect more instructions with incomplete directions, typographical errors and wrong information. Been there, done that!
Good luck with the repair,
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