@#%^! Carb!

Fri Feb 25, 2005 11:34 am

While putting a kit in my cub's carb, I decided to follow Lurker Carl's and Donny M's advice on cleaning and straightening the halves. I was taking my time and doing it right, when an errant file stroke bumped the idle tube. Snap. Sheared off flush with the base. Now what do I do? :roll: :roll: :evil:

Fri Feb 25, 2005 11:44 am

Replacement tubes are still available. With a little care, you can get the old one out.

Fri Feb 25, 2005 1:10 pm

BD is right, It can be done...just requires patience That is why we never allow pilots near the aircraft with tools :D :D

Fri Feb 25, 2005 1:18 pm

Broke mine doing my fixes like in lurker carls web page. I got to excited when I split the 2 halves of the carb for like the 15 time checking fit oops I broke it. I want to say it was $11 or $14 for the tube. I had to drill just undersize by had not with a drill do it by hand. Then I re-tapped the hole it is a #4-48 fine thread.
do not worry it is an easy fix
Chad

Fri Feb 25, 2005 2:48 pm

That is why we never allow pilots near the aircraft with tools


Point well taken. And agreed. I stick to cubs, don't worry!

Fri Feb 25, 2005 2:51 pm

I wasn't aware that thing was threaded in there. What size drill bit should I use. By hand only, as someone noted. Special order from C&G maybe???

Fri Feb 25, 2005 3:03 pm

Use a #42 drill bit in a pin vise to drill it out. Then re-tap with a 4-48 tap. The tube should not be a special order. I believe they are still shown as available stock items.

Fri Feb 25, 2005 3:58 pm

I remember Jim Becker saying that a lot of carbs out there have had the idle tube broken off and still run just fine. I know when I did the carb rebuild mine was broken off so I put it back the same way. Puuuuurrrs like a kitten. :lol:

Fri Feb 25, 2005 5:03 pm

remember Jim Becker saying that a lot of carbs out there have had the idle tube broken off and still run just fine. I know when I did the carb rebuild mine was broken off so I put it back the same way. Puuuuurrrs like a kitten.


Hmmm, if that's the case, what does it do? I'm thinking...leave "well enough" alone then. :o

Fri Feb 25, 2005 5:17 pm

HR my friend,

Fix it right or fix it again :!: :!: :lol: 8)

Fri Feb 25, 2005 5:25 pm

Yeah......don't want problems later. Im off to look for a #42 drill bit and 4-48 tap. 8) But..........what does the idle tube do? Puts the air directly down to the main jet?

Fri Feb 25, 2005 10:59 pm

The idle tube draws fuel for the idle circuit. The tractor will run without it but runs better with it.

With my first Cub, the carburetor was a schizophrenic mess. I always used the junky TSC kits with the wrong directions and missing parts and guessed at the settings using an I&T IH-8 manual that didn't have a breakdown of the Cub carb.

I didn't know the elusive idle tube existed until reading HL Chauvin's hints and some very helpful guys here pointed me in the right direction. I got a genuine IH carburetor kit with the proper directions and GSS-1411. The old tube was broken off and "welded" in the well leading to the main jet with corrosion and varnish - it had to be drilled out as well as the threaded stub in the throttle body.

Fri Feb 25, 2005 11:13 pm

If anyone needs to order one of the 4-48 taps they can go to http://www.mcmaster.com and in the find box type in 2237 (page number) and when you get to the page scroll down to "Chrome Plated Taps".

Fri Feb 25, 2005 11:15 pm

The 4-48 taps are usually available at a gunsmithy shop and fastener places. I bought mine at my local fastener supplier and it cost me a grand total of $2.00 taxes in :!:

Sat Feb 26, 2005 12:42 am

Guess I am lucky, the tube was very easy to remove. I just did it so I wouldn't break it and NOW I see that I must true up the top as it is bent at every place there was a screw.... just like Carl's pictures. So it is a good thing that it came right out.