Setting Float Height on Carb

Farmall Cub Forum -- Questions and answers to all of your Cub related issues.

Moderator: Team Cub

Forum rules
Notice: For sale and wanted posts are not allowed in this forum. Please use our free classifieds or one of our site sponsors for your tractor and parts needs.

Setting Float Height on Carb

Postby Paul_NJ » Fri Apr 01, 2005 1:03 am

Reading through many recent posts discussing over rich carb's, I see I'm in good company. My Cub has run rich since I bought it, despite mixture adjustment, hotter plugs, cleaned air cleaner, float seems dry, etc. I recently rebuilt the carb (IH kit) to no avail. It carboned up the plugs in less than an hour's operation. It also drips gas from the drip port on the carb (for lack of a better term)

The other day I followed Lurker Carl's procedure for setting the float height, but I haven't started it up to see if I did any good yet.

Here's my question.

Initial Condition:
Float Height = 1.34
Float Level = 1.57
Gas Level = 0.53

OK, gas level is on the low side (spec is 0.563-0.625) - so maybe cause of running rich - I'll try increasing float height

Adjusted Condition
Float height = 1.46
Float Level = 1.65
Gas Level = 0.75

Conclusion: Now the gas level is past the spec. I'm surprised it is that sensitive: I increased Float Height 1/8", resulting in a 1/4" decrease in gas level. Is it the experience of those who have done this procedure that it is that sensitive? Maybe I went too far, but I thought I'd try it like this first and see if it runs leaner and doesn't leak gas from the carb.

I'd appreciate any thoughts and experience. Thanks

Paul
51 Cub; IH 340 Utility; IH 240 Utility http://public.fotki.com/PWS/
Paul_NJ
10+ Years
10+ Years
 
Posts: 564
Joined: Mon Apr 07, 2003 11:35 am
Location: Morristown, New Jersey

Postby Lurker Carl » Fri Apr 01, 2005 8:58 am

The float height measurement determines the fuel level inside the bowl. The float drop measurement keeps the float from touching the bottom of the bowl, so make sure the float drop isn't too much.

The float is not a precision instrument, it's a tiny version of a toilet tank shut-off valve. Changing the float level will not correspond exactly with the change in fuel level inside the bowl. I also discovered the fuel level may be a little different each time you measure it - even without doing anything to the carburetor other than draining the bowl to take a new measurement. So measure it several times and see what the average is.

My biggest concern with trying to get the fuel level correct inside the carburetor was to stop the carburetor from draining the gas tank every time I forgot to shut off the fuel at the tank. I figured if I fixed all the leaks inside the carburetor, the fuel drain-down would stop. It worked and the tractor ran better. The key component was replacing the stock needle and cage with the Kohler brand because the Kohler needle is lighter.
User avatar
Lurker Carl
Team Cub Mentor
Team Cub Mentor
 
Posts: 3939
Joined: Mon Feb 03, 2003 9:54 am
Location: PA, Todd
Zip Code: 16685
Circle of Safety Award
Circle of Safety: Y

Postby lonniebug57 » Fri Apr 01, 2005 10:42 am

I think the Kohler needle is the key. Put them in both of my cubs. No leaks since but I still cut the fuel off. Thanks to Lurker Carl for that bit of info.
lonniebug57
10+ Years
10+ Years
 
Posts: 28
Joined: Sun May 09, 2004 3:54 pm
Location: Alabama, Jefferson County

Postby KYMike » Fri Apr 01, 2005 5:04 pm

Got a part number and source for that Kholer needle?
'53 Cub - You can make a small fortune in farming, provided you start with a large one.
User avatar
KYMike
5+ Years
5+ Years
 
Posts: 222
Joined: Wed Oct 06, 2004 10:59 pm
Location: So-Central KY

Postby Lurker Carl » Fri Apr 01, 2005 5:52 pm

I got it from my local lawnmower repair shop, you can put the part number in Google and find an internet supplier. Call the supplier and make sure it's the genuine Kohler kit, not a cheap imitation brand. You will only use the float needle, cage and gasket out of the kit. Here's the info directly from the bag:

KOHLER Genuine Part

25 757 02-S

Kit, Carburetor repair
User avatar
Lurker Carl
Team Cub Mentor
Team Cub Mentor
 
Posts: 3939
Joined: Mon Feb 03, 2003 9:54 am
Location: PA, Todd
Zip Code: 16685
Circle of Safety Award
Circle of Safety: Y

Postby KYMike » Fri Apr 01, 2005 7:34 pm

Thanks, LC!
'53 Cub - You can make a small fortune in farming, provided you start with a large one.
User avatar
KYMike
5+ Years
5+ Years
 
Posts: 222
Joined: Wed Oct 06, 2004 10:59 pm
Location: So-Central KY

Postby WKPoor » Fri Apr 01, 2005 9:48 pm

The float is not a precision instrument, it's a tiny version of a toilet tank shut-off valve. Changing the float level will not correspond exactly with the change in fuel level inside the bowl. I also discovered the fuel level may be a little different each time you measure it - even without doing anything to the carburetor other than draining the bowl to take a new measurement. So measure it several times and see what the average is.


Hmmmmm! :? Seems a couple of months ago I tried to convince others that this bowl level thing wasn't the rocket science some believed it to be. My own in house testing showed how much of a desparety the actual level can be espescially if you check it while the engine is running. I really think I've solved the rich running issue and I'll explain in a separate post.
WKPoor
5+ Years
5+ Years
 


Return to Farmall Cub

Who is online

Users browsing this forum: No registered users and 4 guests