1950 JD B runs rough under load

[JD2450]

Hi all, recently picked up my first 2 cylinder. 1950 John Deere B (gasoline). Not knowing much about them I purchased kind of blind, obviously could do a general mechanical inspection but nothing specific. Been tinkering with it and recently rebuilt the clutch as the plates were chewed up from misadjustment, and the clutch driver was installed on the wrong spline causing a mean shake. Now that that is resolved, i’m having a few more issues I want to ask for some advice on.

Tractor idles fine, hunts every now and then at idle but overall i’d say runs well. When starting in gears 1-3 it runs well. Gears 4-6 (especially 6) the engine seems to almost buck a bit and sounds like it’s running on 1 cylinder until it gets moving decently and then smooths out. I put 2 new Autolite 388s in it because the old ones were pretty black and sooty. Compression read 90psi on cylinder 1 and 80psi on cylinder 2. Adjusted valves with no change. I have a manual and 10psi difference is pushing the limit per the manual, but not sure if that’s causing my issue. Those numbers are engine cold compression with throttle wide open. it does smoke a little bit here and there so i’m sure that low cylinder could use rings at some point in the future. I also removed the carburetor to clean it, everything checked out in there and I adjusted the load and idle jets with no luck.

I also inspected the points and distributor cap. all looks OK - and checked point gap which is within spec. Plug wires are copper core. The governor does seem to be kind of noisy, not sure if that’s effecting anything but I need to look into that regardless unless they typically are a little noisy?

Any help is appreciated. this is a parade / hay ride tractor so it won’t be worked too hard. Just want it to run correctly.

 

[a49deere]

This could be a interesting topic. There is a lot of things that could be causing your problem. The compression you gave is low in my opinion, unless it's an all-fuel variant. New/good engines are about 110 psi. When you say governor is noisy, that is concerning, they shouldn't be noisy. Sounds like you may have a weight issue or bearing issue in it. Incorrect throttle linkage adjustment could be another culprit. When you say you cleaned carburetor, did you take it all apart, brass plugs, emulsion tube, etc. out and get ALL the passages clean with a proper drill bit or similar sized wire? The emulsion tube has a few very small hole that have to be CLEAN to run smooth at load.
To add, I have a 48' A that was totally rebuild, new oversized pistons and tons of pulling power, It also bogs down when first starting in 6th gear unless facing downhill!

These are my opinions only and may be subject to being wrong!!

 

[Fixingfarmer]

Hi all, recently picked up my first 2 cylinder. 1950 John Deere B (gasoline). Not knowing much about them I purchased kind of blind, obviously could do a general mechanical inspection but nothing specific. Been tinkering with it and recently rebuilt the clutch as the plates were chewed up from misadjustment, and the clutch driver was installed on the wrong spline causing a mean shake. Now that that is resolved, i’m having a few more issues I want to ask for some advice on.

Tractor idles fine, hunts every now and then at idle but overall i’d say runs well. When starting in gears 1-3 it runs well. Gears 4-6 (especially 6) the engine seems to almost buck a bit and sounds like it’s running on 1 cylinder until it gets moving decently and then smooths out. I put 2 new Autolite 388s in it because the old ones were pretty black and sooty. Compression read 90psi on cylinder 1 and 80psi on cylinder 2. Adjusted valves with no change. I have a manual and 10psi difference is pushing the limit per the manual, but not sure if that’s causing my issue. Those numbers are engine cold compression with throttle wide open. it does smoke a little bit here and there so i’m sure that low cylinder could use rings at some point in the future. I also removed the carburetor to clean it, everything checked out in there and I adjusted the load and idle jets with no luck.

I also inspected the points and distributor cap. all looks OK - and checked point gap which is within spec. Plug wires are copper core. The governor does seem to be kind of noisy, not sure if that’s effecting anything but I need to look into that regardless unless they typically are a little noisy?

Any help is appreciated. this is a parade / hay ride tractor so it won’t be worked too hard. Just want it to run correctly.

That is actually pretty good compression numbers for a 2 cylinder that hasn’t had a change to the head it should run and not skip.

Often if you have a miss like described and have tried hotter plugs already it is in timing and electrical side.

Distributor or mag?

If distributor try a new cap and wires to your plugs

The answer can also be the same for a mag the wico c could cause some headaches I usually just try a different mag but I realize people usually don’t have them just lying around

Checking timing at the mark on the case and flywheel would be good as well since something was off at the other side of the crank who knows

 

[Loosehandle]

Likely weak spark causing it to miss on one cylinder, anything from point gap to weak coil.

 

[JD2450]

thanks all for the input. Checked out the points again and definetly burnt. Just ordered a tune up kit for the ignition from Steiner, hopefully solves that issue. Will post results once received.

Did some more digging in the governor also - haven’t done any inspection yet but found others had similar noise and found the oil feed hole clogged. Could potentially be that as it doesn’t sound like anything wearing but the sound I would describe as non lubricated gears.

Thanks again!

 

[greenmech]

thanks all for the input. Checked out the points again and definetly burnt. Just ordered a tune up kit for the ignition from Steiner, hopefully solves that issue. Will post results once received.

Did some more digging in the governor also - haven’t done any inspection yet but found others had similar noise and found the oil feed hole clogged. Could potentially be that as it doesn’t sound like anything wearing but the sound I would describe as non lubricated gears.

Thanks again!

I would check the governor hole too and maybe redo the carb behind all those brass screws. Ron MN