1945 B

Having a problem with my "B". It seems like its starving for fuel when I push the clutch in unless the motor is running quite fast. Sorta like an old car when the accelerator pump isn't working. I've been thru the carb a couple times, cleaned all the passages with the drill bits. It will run with either needle valve screwed in all the way so the passages must be clear. Float level is correct. Once its pulling it responds when the load increases, such as coming to a steep hill. Thanks for any help you can provide.

Is there OIL in the Air Cleaner at the correct level..?
Timing is correct..?

All single-throat JDs are "Cold-Blooded" and need some choke while warming up..
You may be trying to operate it a little too Lean.
Try opening the Power screw a couple notches and the Idle one or two notches and see if that makes a difference..
is your Spark good and HOT..?

Ron.

when you went through it did you have the nozzle out and clean those holes out? Also what shape is the throttle plate and bushings in?

If it runs well when you sneak up on the load yet behaves OK when you pull it down (way overloaded) then the problem is as you said like the accelerator pump is not working.

These don't have an accelerator pump though right? Actually they DO have one kinda sorta and I believe Fred is on the right track.

If you pull the main fuel nozzle out you'll find it has cut out cross sections where it is much smaller in diameter than the hole it slides into in the main casting. These cut out areas fill with fuel (by gravity which never fails) when the engine is running on only the idle circuit. When the governor snaps the throttle open, the fuel present in these cut out areas is supposed to be gulped through the side holes in the main nozzle, mixed with air and is delivered to the engine to keep it from stumbling.

If you look in the carburetor from the front past the open choke you'll see a drilled hole going straight towards the rear that is drilled in the very bottom of the air passageway through the front wall or shoulder of the cast venturi. This air passageway HAS to be open for the acceleration well to work! If it is plugged, the engine will stumble falter & fall on its face easily.

When the governor snaps the throttle open, the sudden drop in pressure at the top of the main fuel nozzle causes the fuel trapped in the acceleration well to be forced through the side holes and up the main nozzle as it is replaced by air through this little hole at the bottom front! Once the fuel is all gone from the well the air keeps flowing & is mixed with the fuel metered by the load needle. Some will tell you the main fuel nozzle in the DLTX meters the load fuel but that is not true. ONLY the load needle actually meters the load fuel. The main nozzle in the DLTX only does two things. It (along with the fuel level as set by the float) sets the volume of acceleration fuel and works to vaporize the load fuel mixture as metered by the load needle.

Before I set about removing the main nozzle, I'd make 100% sure that hole (front & center) is open and when air is blown through it... the air comes freely through the main nozzle!

Sometimes the main nozzles come out in pieces. I've not ruined one yet but maybe I'm just lucky. I've heard of people striping the carb then placing the main casting (brass plugs & main nozzle the only parts still in place) in a charcoal grill fire & the next day having it all come nicely apart.

My guess is one or a combination of the following are troubling you. 1, the float level is way too low. 2, the bottom center drilled air bleed hole is plugged. 3, the side holes in the main nozzle are plugged. I would check them in that order.

Hope that helps.

Sorry, I ought to have written FRANKM not Fred!

When I worked on my DLTX34 I followed Roberts Carb video and used a tap that just fit the nozzle and put about 1/4"of threads took a long bolt a couple of washers and a nut and pulled it out no heat at all. just clean out rust the best you can.

Throttle plate & bushings have zero effect. I have several that are worn half way through the shaft & run better than 99% of tractors at shows. Biggest myth in carburetors. Same with a car carburetor. It just doesn't matter. I could go on, had this explained to me by a prominent carb shop also.

I want to thank everybody for their help in figuring out my problem. What it turned out to be was that the nozzle wasn't going all the way up into the carb stem. It seemed to stick a little and then stop. I put the screw into the stem that I had used to pull it out and pushed it in and out. It was sticky near the top. I kept messing with it knowing it shouldn't stick. Soon it was freeing up a little. Then it pushed in about a quarter inch further. Now it extends up into the carb throat about a quarter inch. I remember now that that is the way it is suppose to be. I put it all back together and it runs fine. Always feels good to solve a problem.

Good deal! I wasn't sure what all you had done to it, didn't think about nozzle not being seated right. Merry Christmas!

That has to make you feel great! Thanks for letting us know you found it! Now on to the next challenge!

Later.

When you say "runs better than 99% at shows" I assume you mean under load. I have many carb build invoices to prove your statement wrong. Whether at idle or fast idle, the only place it can get fuel is the two little pin hole ports coming from the idle needle passage. If there is slop in the throttle shaft bushings , worn throttle blade or wear in bottom of carb bore from blade wearing, it will NOT suck fuel up through those ports and will cause you to choke it. I just did a '37 A (18) that no one seemed to be able to get to idle or rev up/down without loud backfiring. With choke just about 1/3 closed it would idle perfectly. Something plugged you say?? Not at all. You could stand there and watch the intake strokes move that throttle shaft sideways minutely. Put in new shaft and bushings (ends fitted to bore curvature) and seal and filled the worn "trough" in the bottom of body and that thing idled / fast idled better than new and no more backfire. People don't put these out in the field and load them down, they putter around in parades and they want them to idle/fast idle like new. You CAN'T get that when they suck air instead of fuel. I don't listen to here-say , I listen to the tractor and I'm sorry I have to disagree with you 100% .

I'll fire it up on Monday & post video if I'm able to be home. My throttle shaft bounces a strong 1/8" at an idle low enough to count fan blades, perfectly smooth. It's a 41 A with a bad head gasket & water in both cylinders, and maybe 40 psi cylinders pressure at cranking speed. It burns oil. It smokes. It runs perfectly at slow idle fast idle instant acceleration & under full load. It's a #53 carb. I have now, & have had in the past, various other tractors & cars & trucks with severely worn throttle shafts. I had it demonstrated to me by a very reputable carb guy that it just doesn't matter. I had a B Jd that was so worn it jammed up- so the previous owner ground down the throttle plate.

Well since I can't post before/after video of the '37 A because it's back at the owners home an hour away,so it would be a one sided comparison at this point. You have your example and I have many. This particular '37 A customer would NOT be convinced and had I not repaired what the other two "carb builders" let go , He wouldn't be my customer anymore either. By the way , one of the "builders" was an old time mechanic at Bader & Sons JD Dealer with many dealerships here in MI. I guess we will have to just disagree on this one as I am not on here to make enemies. You and yours have a Merry Christmas. RB