I Challenge you to make a JD 4010 gas run RIGHT!!!!

JD Seller

Well-known Member
I challenge the fellows that say that they can make their gas New generation JD tractors run GREAT on the gas we have today, MAKE A 1962 JD 4010 gas run right!!!!!

I owned a JD 4010 gas for 26 years. It was used on my feeder wagon the last twenty of that. It ran fine until the oxygenated fuels came out in the early to mid 1990s. After that you had to fool with it all of the time to make it run right. The biggest trouble I had was it would not take throttle unless you had it pretty rich. Then you would have to replace fouled spark plugs every few weeks. Also in warm weather you did not dare shut it off if you wanted to start it in the next half an hour. You could run the battery flat and it would not start at times. The next time it would hit the first roll over. You never knew when it would throw a fit and not start. This tractor got ran over 1000 hours each year at the end. So lower used "show" tractors really do not compare.

In 2005 I decided I was going to "FIX" the problem. I was betting that the motor was just a little to low in compression for the modern fuels. The tractor had 9500 hours and was all original. SO here is a list of what I did to the tractor. It still would not take throttle right after all the work I did to it. I even took it to a fellow that many think is a genus on old JD gas motors. HE is darn good too. He could not get it going either. We both surrendered. LOL

Here is the repair list:

1) The motor had a complete out of frame overhaul. New sleeves and pistons(OEM parts). New cam, as the old one showed some wear on the lobes. Head completely rebuilt(new valves, guides, and seats. All Surfaces planed), Crankshaft was good for going back with standard bearings. Replaced the intake manifold as it was not flat and would not machine flat an have enough thickness in the mounting ears area.

2) The aluminum Marvel-Shebler carb was rebuilt by me first and then sent away to a fellow in PA that had a good reputation on making them run right.(he is dead now). When it did not run right I bought a NEW Zenith carburetor.

3) Replaced the electronic ignition with a new one even though the old one was not two years old. This included a new coil that was from the electronic ignition manufacture. Rebuilt the distributor complete(new shaft bushings, advance springs) New distributor cab and rotor, New solid copper spark plug wires. Several different brands and heat ranges of new spark plugs.

4) When I assembles the engine I adjusted the vales cold and then hot. I double check them with a degree wheel like we did the pulling tractors. Set distributor timing with timing light and then later had a fellow set it with an computer that actually could measure the timing and spark duration. He really could find nothing much on the non computer controlled ignition. We still tried it.

5) Totally rebuilt the governor to make sure it was responding correctly and not jerking the carburetor open wrong.

6) After it still did not run right I tore the motor back down and bought an after market set of pistons that raised the compression. That did seem to cure the hot starting issue but it still would not take throttle correctly.

7) Even thought I had checked voltage at the distributor and coil I replaced the engine harness to make sure I was not getting a heat resistance change in the old wiring.

After all of this the tractor still would not take throttle unless you had the fuel mixture a little rich. If you leaned it out the motor would stumble when the governor opened up. If you increased the load by turning the feeder wagon on it would stumble and almost die unless you choked it or turned the load jet out. With the load jet set to where it would run mostly right, spark plugs would only last a few weeks. I got to keeping a set of new ones in the tractor tool box.

I tried every brand and grade of gas the local stations keep on hand. That was E-10, Premium that was supposed to contain no Ethanol, this was 85 to 95 octane rated fuels. I even tried some E-85 ( had to drain it out as it would not even start on that). The reason I blame the new fuel mixes is I could make it run like new on AV gas. I had 200 gallon delivered and the tractor ran great for two months. It would even run at 95% right on racing "blue" gas. When I would switch back to "regular" gas the plugs would last maybe 15-20 hours.

So tell me what would "FIX" this tractor. Even thought I sold it the fellow that bought it is local and I can buy it back. He only runs it in parades and tractor rides. He found out the hard way that if he is going on a tractor ride to install NEW spark plugs and carry a set with him at all times. He had to be towed in the WMT tractor ride trying to run plugs that where 20-30 hours old.

I tried everything I could think of on this tractor. I spent WAY more money than the tractor was worth just to try and "win" the challenge of making it run right. It is not just this one tractor either. At the same time I was working on mine there where three other local farmers trying to get their JD new generation gas tractors to run correctly. All are cattle feeder guys that wanted to have cold weather starting tractors on remote farms. A list of these tractors: 1968 JD 4020 gas, 1962 JD 3010, 1972 JD 3020, and a 1971 JD 4020. Forgot my 1962 JD 4010. There where a total of 11 different mechanics that worked on all of these tractors. All of them would run on AV gas. None would run right on regular gas. All of us replaced the tractors with diesel tractors.

Now we are talking about NEW generation JD gas motors. Not IH, Ford, AC and etc. gas motors. I can make a IH 656 gas purr like a kitten. So I don't want to hear about how your Ford 8n has been perfect for the last 40 years. LOL Not the brand/type we are having issues with. Even the JD smaller gas tractors seemed to run better than the larger ones. The JD 1010 and 1020s being examples. I had a JD 1010 that I owned for 15 years. I bet that it did not have 3-4 sets of plugs in it over the entire time I owned it.
It sure would be interesting to know what the issue is. I was thinking about this as I just spent a couple hours on my WD45. It runs as good as ever. Dads 2510 required choke even when it was warm. Often my old AC's don't even need choke when cold.
Bob I think it is a fuel air mixture progression issue at the design level. I think the displacement,intake design and carburetor jet size are causing a lean fuel mixture at higher engine RPMs and a rich mix at lower engine RPMs. Never could figure it out.

David G. offered to try and make a fuel injection system on one. If I was 20 year younger I might try it. I have to admit when the fellows on here start talking about the in depth details of how fuel injection works my eyes glaze over and I am soon lost. I just do not have the desire, knowledge base or ambition to "learn" how much of the new stuff works at the in-depth level.
I would try somehow warming the air intake of the carb. To see if im right run a hair dryer close by into the carb while its running and crack the throttle. I would like to think the stumblestall is way better.
John Narragon who owns John's Repair near Trent,SD can make them run nice with a few mods including an MSD box. Though I might opt for a C5 ignition instead of an MSD. Google John's Repair and he will make yours run like an Oliver does.
There are a few things that come to my mind.
On the spark plug issue. You say that if you run it rich enough to take throttle, it fouls the plugs in a short time. This tells me that the plugs you are using are not of the right heat range for the fuel. My suggestion there would be to try some hotter plugs to burn them clean with the richer mixture - at least in theory.
Getting the engine to take throttle with the leaner mixture could be an issue of timing curve. I'm not saying that the timing curve is incorrect, just not well matched to the current fuels. And, I am not just talking about timing setting. There are THREE factors for timing - base timing, centrifugal advance, and vacuum advance. Altering some of these settings may help to alleviate the problem.
Carburetor settings could also be an issue, although to a lesser extent. I might look into resetting the accelerator pump. Richen it up a bit, and it should take throttle better. I would adjust it to a longer stroke if possible, and to begin pumping a bit sooner. Also, do not overlook the check ball in the carburetor body. If it is a bit sloppy fitting, it might benefit from "coining" the seat for a better seal.
As far as warm starting, the one thing that comes to my mind is vapor lock. Check the routing of fuel lines and the isolation of the fuel from engine heat. Could it be that heat from the engine is overheating the fuel causing it to behave badly on an attempt to restart a warm engine?

On the one hand, I see little difference in today's fuels versus older fuels with the exception of the addition of alcohols. Both Ethanol and Methanol. For the most part, the fuel has only one main function, and that is to burn in a controlled fashion to produce power. As far as I can tell, there is no "black magic" or "voodoo" involved. As far as I know, the petroleum coming out of the ground has not changed much over the last few million years or so. The levels of refining and the additives may have changed. But, if you put the "old" fuels and the "new" fuels into a laboratory, it might be hard to find differences in the properties of each one.

Your problems are not impossible to solve. They might take a bit more thinking in terms of where to look for the causes.
Never worked on a John Deere carb, but have worked on other carbs. Back in the60's, when a car would stumble when you stepped on the gas, it needed a new accelerator pump in the carb

Good chance your carb does have such an animal, but needs something to riches the fuel mix.

I had a 62 XKE with3 side draft SU carbs. Each carb had a build shock absorber to prevent them from opening too fast. You may need to rid up a throttle damper or rig up an accelerator pump.

By the way, I had to put a thinner oil on shock damper on the winter.

Good luck, get creative.
That is one challenge that I will "NOT" take....and the main reason I got good at diesel re-powers..
Automotive carbs have two things yours may not. one is a power valve, the other is an accelerator pump. the power valve is vacuum sensitive and progressively richens the mixture as intake manifold vacuum increases at open throttle plate conditions. The other squirts fuel into the intaks during the act of opening the throttle plate. putting a carb of of an engine (like a gas Farmall 806) could be an experiment. Jim
That's strange. I have a 2510 gas tractor and I love it. Gets used about everyday doing chores and is my main winter feeding tractor. It was getting kinda tired so I had it completely overhauled a couple months ago. It starts and runs even better. I have heard the 3000 and 4000 gas engines were junk however. My dad had a 3020 gas he bought new. He never had one nice thing to say about that pile of parts.
well I agree. I would probably try a syringe full of fuel into the carb as I opened the throttle to see if it made a difference, and go from there Many cars made through the mid 70s were running lean to reduce HC emissions, and had drivability issues. I think JD was trying to make their line of tractors produce maximum fuel economy to try to match the expectations of their 2 cylinder product. Not an easy task. Jim Jim
Just a lot of fuel to suck up through a carburetor over a varied load, agree accelerator and power valve would improve it.
The only way I could get my old 105 combine with a 4020 gas engine to not load up was to plug the passageway to the vacuum operated accelerator pump piston. The fuel economy went up too. The vacuum piston has no seals and gas starts sucking past it. There is gas on one side and manifold vacuum on the other side. Downfall to this is I had to open the throttle very slow or it just sat there and popped through the carb when I opened the throttle. Worked OK on a combine, won't work for a tractor where the load is varied so often.

I just read where Roberts Carb claims to have helped with this on the cast carbs. They claim all it takes is some machining and a viton seal. I wonder if they aren't talking about this accelerator pump piston. They claim Zenith has agreed to make the changes and manufacture them.

I forget if the 105 had aluminum or cast, I'll have to run down to the machine shed to have a look at the engine some day. I have a hunch it is cast.
B&D I ran the intake heat selector in the winter position and that helped a little bit but not much. Running hotter thermostats helped some too. I think the ones that worked best where 195 degree ones.
No David just "Eject" it...it is near impossible to get them to run what I would call good,,once you get them on a wide open pull they do okay,, but they are always blubbering and almost need choked a bit when you throttle up..yes an accelerator pump would help..
I have tried carburetors off other brands s and it did not seem to help.

Does anyone know the evaporation rates of the AV fuel compared to the E-10 fuel??? Maybe flash points too?? There is some thing different for the newer fuels to cause the headaches they do.
I was told the 1850 Oliver gas shares the same carb?

I half jokingly tell people Deere quit making gas engines when they quit the two bangers.
Interesting. I had a 69 4020 gas that I had bought used. I used this for hay and loader work for 5 years before selling. This was best starting gas tractor that I had owned (hot or cold). It had 2 6 volt batteries and was told the starter was a diesel starter but I never verified if it was diesel starter. This tractor would start down to zero without fail. It did have a Zenith carburetor and I think I only changed the points and plugs only one time during the 5 years that I owned it. Only used 87 octane gas with ethanol. I'm guessing the previous owner had corrected any issues that it may have had previous to me purchasing?? I bought with 5700 hrs and sold it at 7900 hrs.
Along about that time (late 60s) dad was running an IH dealership. Several time JD customers showed up wanting the stumble fixed on their tractor or complaining about fouling plugs. After several he declined to work on any more JD unless it was a real good customer. I think you have it right it is just an design flaw.
I had an 1850 gas, I
believe it had a Holly
on it. That thing sure
was a finicky b@stard.
It all worked good, but
everything had to be
JUST RIGHT, it was real
touchy if you were
really working it in hot

I had a 4010 lp. Same thing except never fouled the plugs. Changed it to gas with a big aluminum carb. Done like yours. Took some 3/8 id. Copper and wraped the intake just above the carb. Then insulated it then wraped with duct tape.Fixed it after water was warm. Did one more. A 4020. There is a accelerator pump in that carb. But is hard to adjust. My carb was from a G900 MM. PS. Ran hot water around intake. Might have not been clear. Vic
av gas such as 100LL is for airplanes and formulated to be used at altitude and it's a poor substitute for high octane fuel on terra firma, if it doesn't run on Shell 91 it probably isn't going to run on anything else
<img src = "http://i167.photobucket.com/albums/u125/27Grainfield/2320_zps4722923d.jpg">

My gas-powered 4020 powershift, Ingrid, does pretty darned well.

She had sat for a LONG tome with bad gas before I bought her.

The tank is NASTY and I haven't got around to taking it off and cleaning and coating it, so I have an auxiliary tank mounted on the back for now, along with an electric fuel pump.

The carb was unbelievably NASTY. I cleaned it up, bead blasted it, then dipped in it phosphoric acid to stop rust, and installed a new float, inlet needle valve, and accelerator pump from Roberts Carb.

I have never charged the points or plugs in the 5 or so years I've had it, the sparkplugs are not even a matched set, yet the darned thing runs and starts as good as any gas-powered tractor I have ever seen. Surprisingly, the ignition system has never gotten "wet" despite having a front-mounted snowblower. I have a new set of NGK plugs and Blue Steak points for when trouble does happen.

Last Dec, though, the float cracked and I had to solder it. I've got a new one on hand but there's no hurry to change it, right? (LOL!)

So, I guess I got lucky and got a good one!
Cracked float thread
I can't think of a single 4010-4020 JD gas in my entire area....If there was one I'd be glad to call the owners and see what their experience has been with them....There used to be several 3020 JD gas burners around..

Back in the early 1970's I worked at a grain elevator that had a 2 ton Chevy truck with a 366 V-8.....The best mechanics around worked on it and could never get it to run right...It was hard to start and always had a stumble and a miss..It might run right for 300-400 miles and then go back to its old ways..
Ill take that challenge, my 64 4020 gas is now the tractor it should / could have been from the factory.

#1 replace that far too small Delco 10 MT starter with a Delco 25MT. It will now not only crank the engine and hyd pump, it will crank faster than it idles.

#2 Replace that crappy weak stock ignition system with a hot electronic ignition powered directly from the battery. It will now start and run even when the ign system is dew / rain soaked.

#3 replace that Rediculous oversize carb that kills all the tractors low to mid range power and rpm, It will now start / run without belching black smoke, won't foul plugs and runs great at low to mid range loads, while still making good full throttle power.
I adapted the smaller carb from a M Moline model U 283 CI engine. Drivability will go way up and fuel consumption will be way down.
I'm not familiar with the newer gas engines, but what I found smartened my Minneapolis U right up was advancing the timing a little. Turned it into quite the monster on the pulling track. Regular old pump gas, not even premium.
I have a 61 4010 gas I have had for 6 yrs. Has 2900 hrs on it. Put electronic ignition in when I bought it. Has the original carb on it and starts and runs perfect except on a foggy morning. will run rich til it warms up. Haven't ever changed the plugs in it. I have seen them they you couldn't make run tho.
I know exactly what you are talking about JD. I ran one occasionally when worked for Hiniker Co. They had one for a yard tractor. This was before there was ethanol gas but that thing acted the same as you are describing. I never tried to get it running any better nor did anyone else. I just figured it was abused and neglected and maybe needed plugs or points or both. Just a general tuneup. Flash forward to a couple years ago when I was at my neighbors who has a 4020 gas that he said acted like that. I had just repaired his feed grinder and I said lets grind a batch of feed and make sure the grinder works ok. He put the 4020 on it and wound it up to grind corn. I said is that the way this thing always runs? Yep, that's the way it always ran since Dad bought it 40 yrs. ago. Just would not throttle up unless you did it real slow. So I adjust the carb. to where it throttles up real quick and is running under load real good. He was amazed that it was such a simple fix. I see him a couple weeks later and ask if the 4020 still running ok. NO, Loads up at idle and fouls the plugs. Lean carb back down and now you have the hesitance again. So he is getting serious about getting that thing to run right and runs it up to the local repair shop who is experienced working on older JD. Says that's the way they all ran. Only fix is to put different brand carb. on. Forgive me but I don't know what brand they changed it to or from. Long story short, when he got it back with new carb. it ran just as poorly as it did in the beginning. I talked to another friend then who's Dad bought a 4010 gas brand new and he said their's never did run right since new and they have tried 3 different carbs on their's. So I'm convinced the problem is not with carberation as many here seem to think. I think it must be a design flaw in the manifold or valves or total engine design. I think only solution, if you can't live with it is to get rid of it.
Jon Hagen: What kind of total horse power do you now have??? I can't see getting anywhere near the rated horse power with a much smaller carburetor. I think your on to part of the reason the JD new generation gas tractors do not run right. I think the air/fuel mixtures is wrong for any speed but wide open pulling full horse power. So your smaller carburetor is right for general utility type of jobs. I also would think your way short on total horse power. The MM "U" tractor was 40 horse power. The JD 4020 should be 90 Horsepower. So even with drill out the jets you air flow would be too restricted for maximum horsepower. I do think it maybe great for light HP uses.

Have any of you guys replaced the ignitions switch? I had a 2010 gas and it gave some of the symptoms described, replaced the bad switch and it ran and started fine. Also, is the AV gas you are referring to non ethanol gas? I use non ethanol gas in my lawn mower and chainsaw, also in my 2 year old Toyota truck which get 1-2 mpg betteron it.

I suspect the stock carb was much too large to get the last top speed HP out of it for Nebraska test bragging rights. And the vacuum acellerator pump was a crutch that in most cases made the situation worse. I have worked with auto engines that have been fitted with too large aftermarket carbs, In every case, that kills low to mid speed performance and decreases fuel economy.

I have not had an opertunity to dyno my modified 4020 gasser, but it's performance running a 13X70 PTO auger full of wheat is so close to a 4020 diesel pulling that same auger, that I really cant tell the difference. Other than powering those big grain augers, my 4020 spends most of it's time pulling implements that require 1/4-1/2 of what the tractor can produce. Thats where it starts / runs really sweet, at part load.
This summer, 15 years after I added the big starter, hot ignition and smaller carb, I decided to change the plugs, not that it was starting or running bad, but just afraid they might be rusted into the head.
I've been kicking the tires on a 4010 parked 15yrs ago with; you guessed it, carb issues. Really nice looking tractor with 2800 original hours. Wants $2500. 1 remote,swartz wide front. These stories scare me off. Maybe I'll buy it and part it out.
I know the 303 in the old 55 and 95 combines were Dubuque engines, but they always started good, how come? chris
Was the reason for stopping the use of AVGAS price? With your usage of 5000+/- gallons per year it seems that you would be using more than some small airports. 100LL (dyed blue) is available worldwide. Stabilized, non-ethanol, oxygenate-free, etc. If high price was the reason, did you think about blending it with non-ethanol MOGAS? I would recommend a 75/25 mix to begin with and if that works, go 50/50. Just a thought.
(quoted from post at 13:02:36 03/27/16) Maybe an aircraft carb. with mixture control would work !

Unless you richened up every time you throttled up, it would still stumble. Because some people would think of that as a pain, they would consider it a failure (even though it WOULD work). But it would be the bees knees for the parade tractor. Richen it up, start it and warm up, then lean it out for running.

I think the airplane guys use an EGT gauge to make sure they lean out to the right spot, weather and altitude come into play. I dont know if you could get away without one on a tractor but if you are going to change the carb, its not much more money to put another gauge on it.
I only have one 4020 gas that I service but after installing solid state ignition and turning the manifold blocks to winter position it runs good. The starter just grunts over but will start on the second stroke every time. There are a lot of 3010, 3020s around here and with a little work they can run good. Again, solid state ignition with high voltage coil and wires. The Zenith carb is better and I have a machine shop that trues up the accelerator pump bores and makes the accelerator pump plungers oversize so they fit tighter than factory. My Dad's 3020 had this done 25 years ago and was used 3-400 hrs per year up until we sold the cows, now 1-200 hrs. Use varies from disking and cultimulching to blade work and pulling loads. No excessive smoke at any speed. Will start good in cold down to single digits without block heater. I think we have changed spark plugs twice in the last 20 years. I'd have to look but I think it has d-16 plugs in it. I know I had d-21 in it before the ignition upgrade and had to put cooler plugs in as they were getting too hot when disking. You can make them run good but you can't improve the fuel economy, Have to take it home for lunch or it won't make it to the end of the day.
When I drove milk truck,one of the haulers had a Ford truck that had the same problem. That was before automatic chokes. That thing went through two owners and neither one could get it to take off from a dead stop unless they pulled out the choke. The last owner changed the fuel pump,carb,distributor,everything he could think of and nothing ever fixed it.
That was back in the days of leaded gas too by the way.
Bill(Wis) The reason I did not just keep AV gas was mainly the cost and extra fuel tank. I just had enough trouble with it that it went down the road. I replaced it with a diesel JD 4020 and it has been very low maintenance unit.

So the only gas tractors are the antique ones. Just added a Case VAC to that and hope it runs OK. LOL
Put a 3020 carb on the 4020. It will fix everything you do not like about a gas tractor. I did it on my 1850 oliver. It will still run full power and reduce gas consumption.
jd ,, I feel for you ,,.I had a 3010 gasser that was miserable to keep set rite for all the versatile jobs I wanted it todo ,.used to change the heat blox on the intake every season ,p-owner put a blok heater on my gasser 3010 ,,, said it was well worth warming that tractor up good instead of farting with the choke while it buck snorted-fart -belch tried to warm up natural ,.. as others have and will advise ,,, a different carb, will make that 4010 -3010-2010-4020 , run like muther deer intended,,and give it the unmmph too ,,.and far bettr fuel economy than the original equipment that was only meant to burn real gas instead of modernfleapiz
the vac will be ok,,. as they age the 6 volt system breaks down,poor grounds and connections , worn armatures in the starter .... when this occurs they prefer to be crank started ,pull or roll started on a cold motor ,that's what we did when we were kids at home to all our letter series cases ,.warm motor will start easily enuf with electric start , we had a gasser 300 and 511, did not have any problems like that, they would crank rite up even when left for days out in the rain .. the massey 35 was just as good ,,. .the problem with the letter series Case is ,,..the 6 volt starter raids all electric fire from the points and it takes a hot battery to electric crank a case tractor to start... carb wise , they run good ,I baled 1200 bales of hay with my vac last year ,when set rite ,,.they are gutsy as hale.///but whiney and poutin every spring when I try to wake them up from their winter slumber //// as with any gasser ,,,. the more they run , the better they run ,,, leave them set for a month or to , and its az kikin time to get them running rite again ..
I already took that challenge back in around 1990 or 1991 ?
Purposely went looking for a 4020 gas tractor. Found a 1965 model hours showed 5400 ? and it is now at 6000 ? Doesn't get much use but have used it hard a few times. Has a 158 loader on it and a 115 blade. Perfect combo for snow removal and all around use loading and moving things around. didn't want a diesel because I might start it up and run it 15 min. tops sometimes just to load or move something. I still run points and standard 87 octane with 10% ethanol pump gas whatever they sell in Ohio ? Had a few issues with the off idle loading up like you had UNTIL I finally ditched that MS alum. carb. for a cast iron Zenith. Points are still the ones I put in back all those years ago. Spark plugs are autolite 388 and I changed them once but only because I ran it out of gas and then thought I got a bad batch and was not wanting to start. Ended up had a bad transfer pump. I can't begin to tell you how many different tractors I have had in and out of here repairing over the years that everyone else messed with and then they finally brought them to me to get straightened around. I do nothing fancy or use voodoo or anything like that. Just do the basics and go by the book.
I haven't read many of the replies but it sounds just like when you put too big of carb on something that has a long, cold, manifold. This problem was likely started by deere chasing WOT hp rating. I'd bet the propane model has no problems at all.
I would agree that extreme changes in the manifold are probably the issue, it changes the vaporization of the gas quite dramatically.
Convert of find a propane one? Convert to fuel injection? I think you're dealing with an issue that the old engineering doesn't work with the new fuels so you're going to have to use the older fuel or something that mimics it or modify the tractor to operate with the new fuels. I almost wonder if our new cars with the feedback control has allowed the oil refiners to have a little more variance in fuel specifications.
I have a 1981 F350 with 460 and carb. Run the same 87 octane junk in it without issues. Had the truck since 1985.
Triple check that the accelerator pump is actually working on that carburetor. Those 4010/4020 gas tractors liked to backfire hard when shut down hot, that would rupture the diaphragm on the accelerator pump in the big M-S carburetors. Momentary stumbling on acceleration is a symptom of an accelerator pump not working. Opening up the load jet just masks the problem and wastes fuel, as you've already found out.
We had a 2020 gas with that same 180 cid gas engine. The solenoid on the carburetor shuts off the fuel to reduce run-on at shut down, so it always took a little choke for two seconds to start even with a hot engine on a 90 degree day. Started great and ran great if you knew that.
Also we didn't flip the manifold heat block from the heat position to the cold position until we started spring plowing with the tractor. That block got flipped back to the heat setting as soon as the fall plowing was finished.
I am sorry that I cannot offer much on this topic, but I have found this discussion to be quite interesting. I came across an interesting discussion on gasoline on the IH forum a while back. If you look at the Nebraska tractor tests when these tractors were new and run through the test, the gasoline used was 93 octane and it had no ethanol. Today we have 87 octane fuel as the common product available, and this is with ethanol blended in. On our family farm, we have run the ethanol blended fuel since it first was available in the mid-1980's. Our line of gasoline tractors included a 3020 and 4020 Deere, and a 450 Farmall and H Farmall. Back then, the ethanol blended gasoline was rated 89.5 to 90 octane, while the non-ethanol gasoline was typically 87 octane. This would suggest the addition of the ethanol brought up the octane by 2.5 to 3 points. Today, it would seem the gasoline they start with is 84 to 84.5 octane before the ethanol is blended in. What was hard to understand was back in the 1960's and into the mid 1970's, our two big horses were a 4020 JD gas tractor and a 806 IH gas tractor. As the fuel lost its lead and octane ratings dropped, the 806 started to run poorly due to pre-ignition ping/knock. We had to use premium gasoline in that tractor, and later we found a Conklin product that we could add to the gasoline to prevent the pre-ignition. The 4020 is still on the farm, while the 806 went down the road in 1976, with the first diesel showing up then. The 806 had the engine overhauled/rebuilt so many times, the block had been bored to the limit. It was time to say goodbye!

On the JD tractors, the aluminum Marvel Schebler carburetors were how they were equipped. It was found these carburetors were more "touchy" versus those with the Zenith carburetors. The Marvel Schebler equipped tractors seemed to be a bit more stingy on fuel. The cast aluminum Marvel Schebler carbs seemed to "warp" some in the heat and grew more temperamental in their adjustment. Just a few years ago, dad replaced the Marvel Schebler on his 3020 with a Zenith. It starts and runs great, however the horsepower is not quite what is was with the original carburetor, and the fuel consumption has increased. This is not what was expected from a Zenith carburetor from Robert's Carburetors.

I saw in Green Magazine an article about a man who just was getting started with electronic fuel injection conversions for the New Generation Deere tractors with gasoline engines I think the Zenith carb was about $900. The article cited a conversion costing somewhere around $3500 for a 6 cylinder. The improvements cited with this conversion included a 10 percent increase in power and a 20 percent reduction in fuel consumption. This might be the future for the gas powered tractors now over 40 years old. I certainly would not mind having a 3020 or 4020 gas tractor with a reliable electronic fuel injection system. This would fit my yard tractor and winter snow removal needs!
(quoted from post at 14:11:14 03/27/16) well I agree. I would probably try a syringe full of fuel into the carb as I opened the throttle to see if it made a difference, and go from there Many cars made through the mid 70s were running lean to reduce HC emissions, and had drivability issues. I think JD was trying to make their line of tractors produce maximum fuel economy to try to match the expectations of their 2 cylinder product. Not an easy task. Jim Jim
f that was Deere's goal they failed miserably......... and though the 2 cylinder diesel was a fuel miser, the 2 cylinder gas engines were kinda hogs IMO. The 3010/20 and 4010/20 were even worse and the new generation diesels were not that great compared to other makes at that time.

The two cylinder gassers were as good as or better than other manufactures of the era.
The Nebraska tests did not look good as the carbs were dialed way rich for the last possible HP. Instead of a tad lean for the max HP per gallon per hour.
Then again a low compression gasser with a carb an points ignition by design can not be particularly efficient.
Take a look today at the mileage the DI gassers obtain in pickup trucks. Truly impressive.
(quoted from post at 08:27:30 04/02/16)
The two cylinder gassers were as good as or better than other manufactures of the era.
The Nebraska tests did not look good as the carbs were dialed way rich for the last possible HP. Instead of a tad lean for the max HP per gallon per hour.
Then again a low compression gasser with a carb an points ignition by design can not be particularly efficient.
Take a look today at the mileage the DI gassers obtain in pickup trucks. Truly impressive.

The test tractors were all treated the same by the test engineers. My A 2 popper was a gas hog for it's hp. My WD was way better. A WD does have higher compression than a stock A as does a WD45 vs a 60 and so on.

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.