Cub has spark & gas, but won't start!!

[Bob McCarty]

I didn't understand the "t" of holes until this last post. On an IH carb, the drain is the square head 1/4" pipe thread plug on the bottom. The main jet is the brass hex head on the side. The calibrated orifice is at the opposite end of the hex head, that's where the blockage would occur.It's all one piece. Inside the carb there is an idle tube which is like a 1/8" diameter brass straw, there is also a discharge tube that has a hex to allow removal (it inserts on an angle whereas the idle tube goes straight from the top into the bottom and is often broken off). The needle valve under the float can also stick shut (no gas) or have debris which keeps it from closing (gas leak).

[Glen]

Hi,
Here is a pic of what they are saying to do on the previous page.
The main jet is on the lower side of the IH carb. The drain is on the bottom.

Try cleaning the jet's hole with a wire, like the pic shows. First pic is from TM Tractor.

[Mag Man]

This is what Jet looks like.

[RRRRyan]

those are clear, I called it a "t" because of how the holes align. Thx again a lot for the help. It might take a while (I'm getting a slab poured in my barn!) but I'll update this once we've solved it.

[RRRRyan]

Well, I promised I'd update this. It turns out it was electrical after all, so the spark was only jumping without compression. Will try to pinpoint it better but I had a spare magneto with coil, so after swapping off the rotor, & trying a new carb gasket, johnny j (my dad) went ahead and swapped to the other magneto/coil and it started right up. Now we need to figure out how to adjust the clutch. It's a 48 with the internal adjustment. I know there's already a thread on here about that.

[Glen]

Hi,
Glad you got the Cub to run. You didn't say what is wrong with the clutch.
Below is a page from the 1947 Cub owner's manual telling how to adjust the clutch free play.
Notice that IH said to have more than 1" of free play.
1" is what the later Cub manuals for Cubs with the external adjustment say to use.

http://farmallcub.com/rudi_cub/www.clea ... age-40.jpg

Cubs can have the free play increase when the throwout bearing material wears down, the gap between the front of the bearing and the pressure plate fingers gets bigger as the throwout bearing material wears down.

[RRRRyan]

thanks. That's right, much more free play, rough shift from neutral, still moving with clutch pressed. Internal adjustment. Will give it a try soon.