Float adjustment question

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KC2LLW
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Zip Code: 00000
Tractors Owned: 1948 FCUB
2005 NH TC45DA

Float adjustment question

Postby KC2LLW » Thu Oct 12, 2017 9:54 am

Hello,
I have rebuilt my 1948 Cub IH carb and want to make sure I understand the float adjustment. I have made a gauge that measures the float height from the top of the carb without the gasket in place and the bottom of the float should be at 1 13/32". This should have the needle valve open to fill the float bowl with fuel. The float drop should be 3/16" is this where the float moves up until it closes the needle valve and shuts the fuel off from entering the fuel bowl and takes 3/16 of an inch to do so? I just want to make sure of the measurements and how they relate to the fuel flow and fuel level. I hope this makes some sense.

Thanks,
Steve

Bob McCarty
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Re: Float adjustment question

Postby Bob McCarty » Thu Oct 12, 2017 10:13 am

I think you have that backwards. With the carb top right side up, the float drop is when the needle valve is open. The float height is when the float rises to close the needle valve. If you have calipers, 1.4" is the float height, and 1.6" is the drop. An easy way to make a gauge is to take a thin piece of Al about 1/2" wide, cut it to 1.6" long and then notch the other side so it's length is 1.4".

Edited for clarity
"We don't need to think more,
we need to think differently."
-Albert Einstein

KC2LLW
10+ Years
10+ Years
Posts: 16
Joined: Mon Dec 04, 2006 8:38 pm
Zip Code: 00000
Tractors Owned: 1948 FCUB
2005 NH TC45DA

Re: Float adjustment question

Postby KC2LLW » Thu Oct 12, 2017 10:29 am

so then the float height is at 1 13/32 needle is closed float drops another 3/16" needle open? total drop would be 1 19/32? float only move up or down 3/16" to open and close needle?

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Don McCombs
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Location: MD, Deep Creek Lake

Re: Float adjustment question

Postby Don McCombs » Thu Oct 12, 2017 10:32 am

Image
Don McCombs
MD, Deep Creek Lake

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Proud Member of Maryland Chapter 39

Bob McCarty
Team Cub
Team Cub
Posts: 8264
Joined: Tue May 25, 2004 8:02 pm
Zip Code: 80501
Tractors Owned: Cubs, MH Pony, Shaw, Allis G, 1934 Silver King, JD LA and LI, Gibson D, David Bradley Tri-Trac
Circle of Safety: Y
Location: CO, Longmont

Re: Float adjustment question

Postby Bob McCarty » Thu Oct 12, 2017 10:41 am

KC2LLW wrote:so then the float height is at 1 13/32 needle is closed float drops another 3/16" needle open? total drop would be 1 19/32? float only move up or down 3/16" to open and close needle?


Yes, look at the diagram Don posted.
"We don't need to think more,
we need to think differently."
-Albert Einstein

KC2LLW
10+ Years
10+ Years
Posts: 16
Joined: Mon Dec 04, 2006 8:38 pm
Zip Code: 00000
Tractors Owned: 1948 FCUB
2005 NH TC45DA

Re: Float adjustment question

Postby KC2LLW » Thu Oct 12, 2017 11:00 am

got it thank you,

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rockfarmer
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Re: Float adjustment question

Postby rockfarmer » Wed Oct 18, 2017 11:53 am

Bob's special tool takes all the guess work out.

KC2LLW
10+ Years
10+ Years
Posts: 16
Joined: Mon Dec 04, 2006 8:38 pm
Zip Code: 00000
Tractors Owned: 1948 FCUB
2005 NH TC45DA

Re: Float adjustment question

Postby KC2LLW » Fri Oct 20, 2017 10:59 am

Thanks, I rebuilt the carb and set the float she is running like a fine watch now. next thing is to bring her down to the garage clean her up and give her a new paint job. Other then that she works great 1948 Cub with J4 Magneto and 6 volt system, starts instantly hand crank or 6 volt starter.
Steve


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