During my childhood, we had nothing but gasoline powered tractors on the farm. It was around 1975 or 1976 when the first diesel tractors came to our farm. In those years, we had a 3010, 3020, and a 4020 gasoline powered tractors. We also had an 806 Farmall gasoline powered tractor and a 450 Farmall. The 3010 was traded for a 4320 Deere, while the 3020 and 4020 are still in the family.
I have shared my opinions and experiences, mostly centered around the 3020. You will see comments about the carburetor on these tractors. Ours had Marvel Schebler (cast aluminum) carburetors from the time they showed up on the farm, until just a few years ago. Most people will curse the Marvel Schebler carburetors. We did find them more temperamental in terms of keeping them set over the years, and towards the end, as the cast aluminum may have warped some due to the heat, they became even more temperamental. You will probably see comments about getting rid of the Marvel Schebler carburetor and switching it to a Zenith (cast iron) carburetor. You may see strong recommendations about going with a Zenith carburetor sourced from Robert's Carburetor Repair (or other similar types of shops). What we have seen with our 3020 since all this, is we do not have quite the top end horsepower we had before. We have an easy starting tractor which does not seem to "load up" on fuel when idling along. We never had serious issues with plugs fouling ever before, nor do we today. We have a tractor which has become incredibly thirsty on fuel even while under light load conditions. I will share my own personal experience again: In high load conditions, I never thought it was ever possible to burn 7 gallons of gasoline per hour through a 3020 gasoline powered tractor. In performing light load and minor tasks, this tractor has an incredible thirst for fuel still.
You will see comments cursing the use of ethanol blended fuel in these tractors, too. We started using ethanol blended gasoline as far back as the origins of ethanol blends, as I recall, in the early 1980's. The first ethanol blended gasoline products were rated 89.5 to 90 octane. If you were to look back, when most of these tractors were originally built, the Nebraska tractor tests ran these tractors on 93 octane gasoline. Today we are at 87 octane gasoline. And yes, these fuels were enhanced with tetra-ethyl lead, too. The engines were originally designed and built based upon this fuel standard. The lead was removed and the octane ratings dropped. That 806 gasoline tractor would not run properly when this all started and my father had to order premium grade fuels to make that tractor function and work properly. He later found a gasoline additive, which would take care of this problem then. If you look at the end of the muscle car era in this country, those cars had very high compression ratios (11:1 with some closer to 12:1), which needed high octane gasoline for them to function properly. The Clean Air Act got rid of the lead (which was an octane improver) and the octane plummeted. Those cars need high octane fuels. I tend to support the idea these tractors need high octane fuel in order for them to run properly. If you look on the Farmall Forum of this website, there have been numerous discussions on fuels. The older tractors, such as the 2 cylinders and the H/M Farmalls will tend to run okay on ethanol blended gasoline, but there are the criticisms of what the ethanol does to the inside of the fuel tanks and carburetors. These tractors all had lower compression ratios and were designed to run on lower grade gasoline in the first place. The Tractor Vet, on the Farmall Forum, has explained quite a bit as to what happens to the IH gasoline powered tractors (706/806 series) when you use ethanol blended gasoline in them and use them to the extent when they were new. He talks about melted pistons and scored cylinders. He has also mentioned the need for running a high octane fuel in these tractors, especially if you intend to use them in high load conditions. He also shares how lower octane fuels ignite and burn rapidly and hotter, as compared to a high octane fuel, which burns cooler and ignites slower by comparison. I believe the 3020 and 4020 tractors had a bit lower compression ratios as compared to the 706 and 806 Farmall tractors. An ethanol blended fuel does have a lower BTU heat content, versus non-ethanol gasoline. I believe E-85 has only about 2/3 of the BTU heat content versus straight gasoline. I think if you do the math, E-10 ends up around 95 percent of the BTU heat content versus straight gasoline.
Our gasoline powered tractors were used regularly on various tasks for a number of years before, and for a number of years since. They did daily livestock feeding chores year around. They were used for cultivating. We used them in the fall of the year for hauling grain out of the field or hauling silage from the field to the silo. We loaded and hauled manure with these tractors. Since there is no livestock anymore, their use has grown more restricted/limited. I think some of our carburetor and operational challenges began when our 3020 was being used less regularly, as the gasoline certainly is in the fuel tank longer than before being refreshed by burning it through the engine as much as it had been before.
I have also seen some criticisms particularly directed towards the 4010/4020 gasoline tractors, in mention of the long intake manifold and the carburetion not necessarily being optimum for all 6 cylinders. I have read in order to get the air/fuel mixture optimized (along with temperature) for cylinder 1 and 6, the ones in between end up being over fueled. I have no firm opinion on this at this time. I have also had a couple of conversations about the Zenith carburetor, in how it has extra fuel passages or ports, which contribute to excess fuel consumption. I struggle with how this same carburetor is used on other brands of tractors, with less of a thirst for fuel. I ran a 706 Farmall for a neighbor in the 1980's, which was rather stingy on fuel, for a gasoline powered tractor.
Is everything I shared above pertinent? I am not sure. I think they all have merit. I am puzzled with what I have experienced with our 3020. I am intrigued with the gentleman who has started producing electronic fuel injection systems for these John Deere gasoline powered tractors. As I recall, he has cited a 10 or 15 percent increase in horsepower, while reducing fuel consumption by a similar percentage. I believe the cost of this, at the time I read about it, was around $3000 for a 4010/4020. It would take a lot of gasoline and hours of running time to recoup those costs. I also know the Zenith carburetor put out by Robert's Carburetor, has a cost of $1000.
