John Deere B governor surging, running rough

Seeking advice on a 1948 John Deere B gasoline model that is running a bit rough, especially at idle. I had rebuilt the carb back in September but haven't run it much since then. The tractor ran ok before the carb rebuild but there was a fair amount of dirt in there (the top two hole in the main nozzle were clogged solid). Now I am noticing a lot of what sounds like the governor surging when the tractor idles. Turning out the idle needle seems to correct this. However, in order to make her idle more smoothly I have to turn that idle need out far more than the 1 1/2 to 2 turns recommended. As such there is a lot of black smoke when you put the clutch in from it running rich. Any suggestions as to what I might tweak or does it sound like it might need governor work (which wouldnt be surprising since it had a governor mount live pump on it for some time). Thanks,

Peter Markel

ran ok before u cleaned carb, and now it doesn't! sounds to me like u moved the dirt around in there somewhere

Did you remove all brass drill plugs and drill all passages out? Are throttle shaft bushings tight,IE no rocking sideways of shaft? Did you get nozzle ALL the way back up in it's bore,IE approx 3/8" up into throat? Set throttle lever as far open as you can and still stay running and then close load needle. It shouldn't make any rpm difference. If it does then you have plugged passages yet. Probably not governor. The fact it's surging verifies gov is working. It's either sucking air (bushings/worn throttle blade) or it's taking gulps of fuel from load nozzle when it slows down and then speeds up to burn it. Do the test I mentioned. It will self diagnose. If it doesn't run nice at 3/4 throttle after you've shut load needle then needs drilled or air leaks fixed.

Rigid adherence to recommended turns out has always been a pet peeve of mine. They aren't carved in stone to begin with, they are approximate initial settings that should allow you to get the engine started. Beyond that, and ONLY that, they are to be forgotten entirely.

You don't seem to understand this so I can say that it's out of adjustment and have a great deal of traction doing so. Each mixture screw will affect the other range, turning out the idle to improve the idle will cause the load side to be richer too. So as you correct the idle, you are also skewing the load mixture by some x amount and it should come as no surprise that it will need tweaking too.

I set the load screw by flipping the throttle wide open from idle briefly. I can usually tell if it's too rich (excessive black smoke) or lean (backfiring, stumbling) and adjust the load screw very closely by this method with final tweaking of the load screw done under full load in the field. I do have slight smoke at both idle and full load ignoring sudden changes in smoke from sudden throttle movements.

Excessive weight has been given to the turns out count from day one when both of us were not in the picture at all, it's just human nature to want to document the weight of a gnat too. Some things are rather pointless, turns out tops my list. But of course, that's where I set them first time every time.

(quoted from post at 19:55:50 10/26/16) Did you remove all brass drill plugs and drill all passages out? Are throttle shaft bushings tight,IE no rocking sideways of shaft? Did you get nozzle ALL the way back up in it's bore,IE approx 3/8" up into throat? Set throttle lever as far open as you can and still stay running and then close load needle. It shouldn't make any rpm difference. If it does then you have plugged passages yet. Probably not governor. The fact it's surging verifies gov is working. It's either sucking air (bushings/worn throttle blade) or it's taking gulps of fuel from load nozzle when it slows down and then speeds up to burn it. Do the test I mentioned. It will self diagnose. If it doesn't run nice at 3/4 throttle after you've shut load needle then needs drilled or air leaks fixed.

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hanks for the advice, I did the idle load test this afternoon. Sure enough at full throttle, the tractor died when I closed the load needle. That's indicative of a blocked idle passage? I removed all the brass plugs when I rebuilt it and let it sit first in gasoline for two days, then in a multipurpose cleaner for two days. I let it dry and snaked a length of fishing line through the passages, then blew it out with compressed air. Of course I could have missed a passage.

To do it right, you really need the drill bits because rust will not break down in gas.

Yes it indicates plugged idle passage. Remove idle needle and stick a fine wire down through where idle needle point seats as far as it will go. Now remove the little brass plug (the upper one if it has two) down in bottom of stem just above threads. Now with a fine light, look in through the hole where plug came out and you should see an even smaller dia hole and at the end of it you should see your wire end. You probably can't. This is the secret idle passage that no one gets drilled out right or deep enough. If you can't see your wire then it ain't drilled far enough. Also the upper drill plug on manifold flange needs to come out and long drill bit run horizontally all the way in to the drill plug hole to the right of the idle needle threads. It's a #53 bit for the little secret passage in stem and # 40 for the long horizontal passage and the verticle passage to the right of idle needle. Sloppy bushings and/or worn throttle plate will let it suck air instead of fuel through idle passages causing same problem. It has to suck fuel 5" through very small passages before it ever gets to carb throat/throttle plate.If you don't want to do all this just send it to me and you will have one sweet running/idling "B" . My e-mail is open for details/questions.

(quoted from post at 18:47:27 10/27/16) Yes it indicates plugged idle passage. Remove idle needle and stick a fine wire down through where idle needle point seats as far as it will go. Now remove the little brass plug (the upper one if it has two) down in bottom of stem just above threads. Now with a fine light, look in through the hole where plug came out and you should see an even smaller dia hole and at the end of it you should see your wire end. You probably can't. This is the secret idle passage that no one gets drilled out right or deep enough. If you can't see your wire then it ain't drilled far enough. Also the upper drill plug on manifold flange needs to come out and long drill bit run horizontally all the way in to the drill plug hole to the right of the idle needle threads. It's a #53 bit for the little secret passage in stem and # 40 for the long horizontal passage and the verticle passage to the right of idle needle. Sloppy bushings and/or worn throttle plate will let it suck air instead of fuel through idle passages causing same problem. It has to suck fuel 5" through very small passages before it ever gets to carb throat/throttle plate.If you don't want to do all this just send it to me and you will have one sweet running/idling "B" . My e-mail is open for details/questions.

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hanks Randy. Those bits are available from Robert's Carb repair I believe. Are they to be turned by hand or by a variable speed drill?

Turned only by HAND.

The small one for secret passage...hand only...the larger one I use variable speed drill because you are only enlarging passages back to their original size as apposed to drilling through a completely rust filled hole like the secret passage usually is.Just use your common sense .