Plugs for a John Deere B

[Todd B]

I have a 49 or 50 John Deere B. Not sure exactly what year because the serial number tag has been missing for over forty  years.  I run only Shell Premium fuel and lately it’s been very hard to start.  Once it starts, usually after a backfire or I pull it to start it runs perfect. I have a good strong 12 volt battery, spins like a top but just don’t want to start. I took the plugs out and wire wheeled them, set the plugs at .030 and it starts kind of ok for a few times and then the same problems.  My dad had this tractor engine rebuild 45 years ago and it is always ran great. Just frustrating the hell out of me the last couple summers.  
Any thoughts? 

[pflaming]

If the carburator has a pet cock under the bowl, drain some fuel before you start. You may find a small amount of water in there. Also, those tractors started on gasoline, then ran on what was termed “tractor fuel” which I think is similar to kerosene. Hi test gas might be too hot. I grew up on these tractors. Good luck, that two banger sound is music to my ears! 
 

our fathers tractor. We found it four years ago and had it restored. 

[Dave72dt]

I think the gap on the plugs used to be .025.  Take a good look at the magneto.  It has a set of points  and the spring for the impulse can get weak and/or break, as well as cracks in the coil.  Finding anyone who can test or repair a mag could be a difficult search but there has to be some collectors out there that can help.

[pflaming]

Dave may be correct, and conditions in wetter, more humid environments may affect the magneto.
 

I lived in Western Nebraska. We had two Model D Jon Deere tractors, two  combines, two MM tractors, two IH tractors, one AC tractor and other engines with magnetos. We never had one Magnito failure and never adjusted or even checked the points. 
 

Im not criticizing Dan, just relating my/our western Nebraska experience. However every machine that had distributors had match books in the tool box, the cover was the proper width for setting points. I’m 80 years old I knew how to set points when I was 14 years old when I started putting in long days and weeks of tractor driving. It was a fun life to be able to play with real toys, plows, cultivators, grain drills, corn listers, sickle bar hay mowers, side delivery and dump rakes, balers, skip loaders.

 

At age 12 I knew how and when to pull a calf, how to push it back into the womb, out my hand into the cow to turn the calf around so the front feet and nose come out first, knew where to drive a sharp knife into the first stomach of a bovine to release bloat, how to casterate, dehorn, and give shots to animals, etc., make butter, slaughter chickens, etc. life was quite different then. To this day I dislike urban living, crowds, cities, and vehicles in which I can’t hear the engine run. And new paint.

 

sorry for the history lesson, but that’s who I am and I guess the way I am.  Different strokes for different folks. 

 

 

[Todd B]

1 hour ago, Dave72dt said:

I think the gap on the plugs used to be .025.  Take a good look at the magneto.  It has a set of points  and the spring for the impulse can get weak and/or break, as well as cracks in the coil.  Finding anyone who can test or repair a mag could be a difficult search but there has to be some collectors out there that can help.

I was wondering if the magneto was getting week also. When my father was alive he preached to me constantly never ever touch the magneto. He said it was extremely sensitive, so I need to find the John Deere god in our area. I was hoping  to start with new plugs.

 

[HotRodTractor]

I'm a few days late - but I would send your mag to Rudy Calin - I've seen some good work out of him in recent history. I've never used him, but that is where my next mag is going. http://www.rebuiltmags.com/ Unfortunately my old mag guy doesn't do them anymore - its a shame as he was only 10 miles down the road. 

 

As for plugs - I would use some Autolite plugs they seem to work the best for these old Deeres. Its all I run. I believe the proper plug is a 3116 for the B - but I would double check that. 

[Todd B]

I put new champion plugs in that John Deere recommended.  Still won’t start good. I’m pretty convinced it’s the mag also. I found someone local that thinks he can handle it. Thanks for your Help 

[Plymouthy Adams]

lots of reading on weak spark of the magneto or any permanent magnet ignition....weak spark is often related to loss of magnetism...while a magnet can be restored it requires a special setup and from what I have read, often is not costly to be rejuvenated.  

[Dave72dt]

My father used to convert weak mags over to a conventional coil.  He didn't share with me exactly how he did it but if you have battery, starter and gen on it, it's doable. It can still be done if have a hand start and can mount a battery.  It'll just need to be recharged on a regular basis.

[Todd B]

My dad converted it to 12 V 40 some years ago. He has an alternator on it but still uses the Mag. It’s been on  my property for 32 years and always started awesome. Just this last couple years been giving me grief. 

[Mike36]

Todd, you need to contact Roberts Carburetor Repair, Spencer , Iowa. As the owner of 8  John Deere 2 cyls, I have dealt with them many times and they are top notch. You can send the mag to them, or they will sell you a CD showing how to rebuild it yourself. They have every part needed to do this, and can recharge your magnet which I suspect is your main problem. I would also throw away the Champions and put Autolites in it. Roberts phone....712-262-5311, they also have a free catalog.

 

[bones44]

Back in my tractor pulling days I ran nothing but Champion plugs with no problems. as stated: Different strokes for different folks. 

[Plymouthy Adams]

different strokes for different engines...…..lol

 

not sure of today's line of Champion....can't be all bad as they still in business....I believe they are Mopar suppliers of stock plugs yet today....just had some bad experiences in the past when it was our primary line of ignition parts in the shop...hard to get over the amount of rework we had to do because of plug failure...often at the rate of two out of 8 and always at different intervals...but usually within 10 days or so of the tune up.  

[Todd B]

 I bought a new coil, points, condenser and gaskets. Rotor got back ordered. I installed everything and starts right up now.  But, at halve throttle the rpms seem to go up and down. Could that be from the rotor, the old one doesn’t fit snug so Is that the variations??

[48Dodger]

I imagine your model has a pressure release valve for hand cranking? Maybe a leak has developed?

Just thought I'd mention it.

 

48D

[rockingjd]

Started playing with 2 cylinders back in the 80s. Dad and I have collected a few since then. I don't like Champion plugs but that's just an opinion. I found out the hard way not to use modern high resistance plug wires on a mag. Our AR would not start unless pulled. Problem was solved by switching to copper core plug wires. 

[Todd B]

I thought about changing plug wires because if there’s even a mist outside the tractor will stop running. Good to know, thank you. 
 

i’ve had my dad‘s tractor at my shop for the last 33 years. When he was alive he had a muffler that really muffled  the sound of it. I wanted to change the muffler so it had more of a deep sound like a John Deere should and he said not as long as I’m alive. When he died 10 years ago one of the first things I did was went to John Deere and got the proper muffler. Sounds awesome under power. 

[rockingjd]

My Dad baled hay for several years with a 730 diesel that I put a cut down 6" transport exhaust on. Neighbours on the next concession liked the sound. Not just because of this but Dad has hearing aids now. 

[Dave72dt]

Because the throttle lever controls the governor, not the carb, take a look at the governor.  It may stick a bit or over time has worn a bit and created a spot the governor arm wants to stay in.  Worn linkage in any part in the gov, from gov to carb, loose throttle shaft itself can impact how stable the rpm will be.