scratching my head and out of thoughts on JD G.

[Northeast Puller]

I went to a benefit pull 6 year old boy with cancer.I thought I had this problem fixed but know way.My 1949 JD G when on a hard pull or up steep hill will skip a beat or 2.It is mostly stock with cast piston in it at 65 and 68 cranking PSI hot wide open throttle. Has good fuel flow. Dry air cleaner and have removed 50 years of junk from the air stack and carb pipe I have put the electronic ignition .coil and wires from CBS performance that did not help the problem . I have Autowlight 388 in it gaped at 35 or 40 thousands and and have tried both gaps.I have had the big nut carb off and cleaned using the drill bits and replaced the out of round venturi and put all new gaskets and plugs and new load needle's in it. The did not help . I ran it with better then 3/4 tank of gas for the heck of it and that did not help.The plugs burn a gray whitish color. First pull it missed under heavy load. I open the load screw up 2 clicks on the next pull and it missed even more. The load screw is set at 1 and 1/4 turns out as the book and Roberts carb said. So what rock have I not turned over on this problem?I am getting stumped and frustrated at this problem. I have even advanced the timing some and that gave me some more power but did not fix my problem either. Thanks for any help with this. If I could find a dynow and work the snot out of it maybe I could get to the bottom of this but just trying things at the next pull over the last 2 years is not getting it dun.

 

[John T]

That load screw is best adjusted if you could couple it up to a real load like a fan or dyno or heck a loaded down mixer/grinder etc if possible. Was she throwing much if any BLACK smoke when she missed?? If not Id open the load another couple clicks or so n try it, but if it was then conversely Id screw her down n try it.

You have any idea where the timing really is at fast to mid range RPM ?? If not, Id be using a timing light and observe it. Ima thinkin fuel/carburetion for now versus ignition but thats a stretch based on limited info n not being there. I guess the carbs float level is right ?? and if you open its lower drain plug n turn the gas on you get a good constant stream for at least a minute?? Was the carbs cylindrical fuel inlet strainer and its screen etc all cleaned???Was the main center vertical brass nozzle removed on the carb n cleaned?? I guess it was if you did all you claim.

John T

 

[Northeast Puller]

John T I have yet to foul a plug on this tractor. If I open load screw up a lot more it will run rough and quit but will not blow black smoke. I have set the timeing with a Snap on advanciable timeing light hot at idle and checked it for the mid ranges. The distribitur advance appears to be working.

 

[John T]

Hey, I'm about out of ideas also, still sounds like a carb problem about which I'm not smart enought to help other then my comments below. I would expect it to black smoke as you open the load needle??? Float level or main center brass vertical nozzle or the carbs side cylindrical strainer as already mentioned is all I can think of, sorry GOOD LUCK JT

 

[Mike Aylward]

NP, one thing about your post is puzzling me. You mention "replacing the out of round venturi". There is not a removable venturi in these carburetors. What part are you speaking of? Mike

 

[Mike Aylward]

NP, is it possible you have the main nozzle installed upside down? It will go in either way but the flat end goes toward the carburetor throat (or up). Installing this part wrong can sometimes cause the symptoms you describe. Hope this helps. Mike

 

[Duane Larson]

Northease Puller,
There is a small hole (#59 drill) on the carburetor neck between where the load needle seats and the top of the bowl nut threads - is that hole open? It acts as a baseline fuel feed to the load circuit on a 51.

 

[Northeast Puller]

Thanks John T for trying. Duane I will check that out again.Mike the part I called a ventory is the brass nozzle in the center was egg shaped some.I straited it up to round shape using a nail set. I put it back the way I removed it but it could be in backwards.This carb has an unfavorable rebuilders tag on it that is noted for poor work and bad customer relation but I am not going to bad mouth him by name as some one else may have jiffy ed this up after him and before me. When I opened the carb to clean it had about 9 raps of teflon tape disintegrating on the threads of the float bowl needles shaft brass slotted screws.I put O rings on it when I put it back together.

 

[wilamayb]

It certainly sounds like you are running lean.

I'm guessing you have looked through the nozzle to make sure none of that teflon is covering the end?

You mention good fuel flow. How did you determine this? If you loosen the valve on the bottom of the bowl it will run fuel until the bowl is empty which would give the idication that the fuel is flowing well. Leave the valve open for 30 seconds or so. Did the fuel flow remiain strong for the entire time? If not check the screen in the top of the sediment bulb on the bottom of the tank.


If you cant make black smoke then you have a definite fuel problem. It should make a haze of black smoke at full throttle (when in a pull when the carb butterfly is wide open, not just rated speed) if you open up the load needle too much.

 

[Northeast Puller]

Wilamayb I used Old Clooney and John T method of a pencil size stream and can fill a coffee can pretty good from the bowl drain.Duane and Mike I did the Pat B thing with the clear hose to recheck my float level after that I pulled the carb off and checked that vent again with the drill bit. I double checked the nozzle and it is put in correctly with the shoulder up and the angled cut down. I have blown air thru the small holes in the gas cap to check that venting action. Tomorrow I may drain the tank pull the glass bowl off and make sure that I do not have a restriction in the tank neck or glass bowl. I am going to use my friends camera scope and look in the tank to check for ping pong balls and any thing that good get sucked over the out let hole.I thought about putting in the plug inserts in to run the new type auto plugs as the auto light may not take the big coil. I have had plug troubles lasting on my 1948 A and the G. It is my understanding Auto light is now making them in Japan or some place and they are getting to be like the champion D 21 will not take the punishment either. Do You no what NKG or other plug would be best ? It is my understanding with the in certs you need a plug with a longer electrode to get to the cylinder edge.

 

[Rick L.]

sounds like a lean mixture, next time you get to work the engine pull the choke on a little see if that helps, if so your not getting enough gas.