Farmall Cub

I have 2 IH carbs. I have rebuild both of them but still leaking fuel. I ordered the Kolher needle valve that I was tood would fix the problem. But it is to tall . The float wll not fit on the carb with that part. what do I do?

Bob, Check this link to the FAQ page 7. It has both the piston ring numers and the Kohler needle valve number along with other valuable part cross references.
http://www.atis.net/CubFAQ/cub_faq.html#q7

I have been battling this as well. The Viton tipped needle didn't stop the leak. I think it's coming in around the threaded portion of the cage or the threaded portion of the main fuel nozzle. Both areas are submerged in fuel and the seats where the gasket sit are a bit rough.

I'm going to play around with thread sealants, compressed air and soapy water to chase down this gremlin.

Lurker Carl wrote:I have been battling this as well. The Viton tipped needle didn't stop the leak. I think it's coming in around the threaded portion of the cage or the threaded portion of the main fuel nozzle. Both areas are submerged in fuel and the seats where the gasket sit are a bit rough.

I'm going to play around with thread sealants, compressed air and soapy water to chase down this gremlin.

Carl,

I'm glad someone is finally following through with the suggestion. A very small amount of sealant applied with a toothpick will work wonders. I don't know of a way to check the fuel nozzle for leakage, but the test of the seat washer was dramatic proof of where the common problem really lies. I use sealer on both sides of both washers to be sure.

I've been having trouble with the viton needles sticking, so I'm back to using the originals.

Hint: Use one pound of pressure or less. The soapy water is in a squirt bottle.

George,

I did something very similar about 30 years ago to find why my Rochester 4GC was always flooding on the secondary side. After replacing the needle and cage several times, it was apparent that the needle was not the problem. It was the cage gasket leaking because the seat was gouged. Then I applied the same theory to a fuel dripping Marvel-Schebler on a Massey-Harris and it worked there as well.

Just like with the MH, I think the cage is the culprit here since it remains under pressure from the fuel load in the tank. With my first test, I used teflon tape on the Cub, but that didn't work. I'm going to try Permatex next. The fuel nozzle is not subjected to pressure so I'll check the fuel nozzle by filling the fuel bowl up to the top and seeing if anything seeps past the gasket over time.

I'll keep y'all informed.

LC

While pressure testing thousands of aluminum dipoles in the field, we used soapy water. Big mistake...Soap is very corrosive and unless the parts are rinsed throughly the aluminum will corrode. White powder everwhere. Since then I use a product called Snoop, it's a noncorrosive leak detector.

Like a brass wire wheel on aluminum, Snoop is my preference for leak detection.

I certinly agree with Donnie about the soap' When I was in school in wood shop after predrilling a hole the teacher had us use a little soap on the screw and that made it turn easer and helped from splitting hard woods. so I remembered that when remoldeling my Kitchen cubords and cense have had to replace all the hinge screws. I don't know if it's the modern day soap or what but I just couldn't believe it.

WE USED SNOOP TO CHECK NATUARL GAS JOINTS FOR THE THIRTY PLUS YEARS AT MY JOB. ONLY OUNCES OF PRESURE. IF THERE IS A LEAK IT WILL SHOW. IT IS AMAZING HOW LONG A BOTTLE WILL LAST.
BILL