Super A Zenith Carb issues?

[Super A]

To begin with, please remember I'm a novice that enjoys turning bolts. That does not mean I always know what I'm doing!

I recently got this Super A for "parts." But it's too nice to be parted out. I wanted it for the "correct" Touch Control for my '47 Super A, so I'm going to swap the '50 model Touch Control on my '47 to this one and keep it for a while.

The carb needed to be cleaned out, the tractor wouldn't run so I took it apart for cleaning. Squirted carb cleaner through all the holes in it and then I put it all back together and it ran beautifully if it was about half choked. If the choke was full open, it stuttered and stumbled.

So, I took the carb back apart and completely disassembled it inasmuch as I took every single jet out of it, soaked it in a can of carb cleaner, then blew it out with carb cleaner again. I discovered the discharge nozzle had a crack in it about halfway down the lower half. So, I replaced it, cleaned the carb again, and put it all back together. It runs better with the choke full open, but it's still not just right.

The tractor was originally a kerosene burner and still has an adjustable main jet. Screwing it out a little also seemed to help, but not completely.

The only question I have is this hole that is circled. It appears to go down into the main jet passage but no carb cleaner seems to spray out anywhere when I spray into it. Should it connect anywhere in the carb?

I did notice that if I adjusted the idle adjustment screw, there appeared to be no change in how it ran.

I did check the tractor with a known good carb, and it runs fine with choke full open. So, I know the issue is the carb.

What am I missing?

thanks,
Al

[Jim Becker]

I believe you are pointing at the idle well. The bottom of it should go through a restriction then open into the area behind the main jet. It should line up with the passage in the upper half that contains the idle jet. From the idle jet, the opening should go up to the idle discharge port, which is next to the throttle plate. If this passage is plugged, fuel for idling will be cut off.

[Super A]

I believe you are pointing at the idle well. The bottom of it should go through a restriction then open into the area behind the main jet. It should line up with the passage in the upper half that contains the idle jet. From the idle jet, the opening should go up to the idle discharge port, which is next to the throttle plate. If this passage is plugged, fuel for idling will be cut off.

Thanks Jim, that makes perfect sense. Do you think that passage being plugged would affect the stumbling with full open choke?

I was gonna hit it with compressed air but couldn't find by blow nozzle......

Al

[Jim Becker]

I suppose so.

[Super A]

I think I figured it out! 100 PSI through that passage did NOTHING. I had a set of the teeny-tiny long drill bits used to clean out a Marvel Schrebler carb on a JD H. So after some gentle probing--followed by some tougher probing and twisting the bit, I started digging out some rust/crud. Finally got it so air would pass through. I put it all back together and the tractor seems to run well now.

Now to get the touch control swapped to my '47 so it'll be "correct!"

Al