Recently there have been several requests for information about changing an LP tractor to gasoline and changing a gasoline tractor to LP. Each person has his reasons for making this type of changeover, but let’s first ponder a few considerations before making a commitment to one fuel type or the other.
First to consider is the fact that, in most cases, you will be altering the tractor from its original “as shipped” configuration. Another consideration is the cost and availability of parts; it’s always wise to gather all of the parts necessary before you begin the project just in case you run into a very hard to find part. Having a parts manual will prove to be a very great asset for a project like this.
Many people seem to object to LP tractors for two reasons. First, many people don’t care for the look of an LP tank standing above the hood. My first reaction to that is—have you looked at a New Generation 3010 LP tractor (Photo 1)? The LP tank is under the hood just like a gasoline tank in this 3010 gas standard (Photo 2). Any other make or model tractor that I know of will have the LP tank standing above the tractor hood (Photos 3 and 4).
The second reason some folks object to an LP tractor is the refueling issue. Granted, refueling an LP tractor requires an LP liquid pump, which most of us don’t have. When LP tractors were working every day, most farmers had their own liquid LP pump attached to the bottom of an LP tank or had an LP tank with a liquid tap on top of the LP tank. We had an LP tank set up on the farm like this with a liquid LP pump, which worked just fine. Wish I would have kept that set up when the last LP tractor left the farm.
Both gasoline and propane are dangerous fuels if there is a leak so I don’t think any of us can make a claim that one or the other fuel is more dangerous than the other. Both fuels are safe when handled and stored correctly. For ease of refueling though, gasoline will have the edge over LP. Beyond that, there probably are more advantages to LP fuel. We all know gasoline goes bad in a short period of time, while LP can be stored for years and remain perfectly usable.
How about the octane rating for gasoline and LP? Typical regular unleaded pump gasoline we burn in our cars is 87-88 octane while LP is 104. Because of this difference in octane ratings in New Generation and two cylinder tractors, Deere ran a higher compression ratio for LP tractors. There was a second reason for the increased compression ratio with LP tractors. There is less energy in a gallon of LP than a gallon of gasoline. By increasing the compression ratio of LP tractor engines, Deere was able keep the horsepower of the gasoline and LP tractors nearly identical. Another advantage for LP is how clean it burns. A quick look at the basic chemical formula for each fuel will help show us why LP burns so clean. The chemical formula for LP is C3H8 while gasoline is basically C8H18. Okay, for the chemists, yes—there are other additives in each fuel, we just mentioned the base chemical. The lower carbon content of LP is what allows it to burn as clean as it does.
How about fuel costs today? Currently, regular unleaded gasoline is at $3.75/gallon in this local area and LP is currently $1.18 in northeast Wisconsin. See any advantage here?
Let’s first take a look at converting from LP to gasoline since this is the easiest conversion of the two conversions we will look at. For this article, we’ll look at a New Generation 3010, but the basics will apply to all tractor models. To go from LP to gasoline, you will need the following parts—a gasoline tank, fuel line from the gas tank to a new fuel pump (Photo 5), you will need a fuel pump on New Generation tractors because LP tractors don’t use a fuel pump (Photo 6), fuel line to a new carburetor with either an inline filter or sediment bowl, a new gasoline intake manifold (Photo 7) and a gasoline hood for non-3010 model tractors. On nearly all New Generation and two-cylinder tractors, the air cleaner and intake tubing will be the same; the 4020s will be an exception. The throttle linkage will also remain the same with gasoline and LP.
When converting to gasoline from LP on New Generation tractors, you will need to remove the liquid and vapor control rods with their respective valve handles. Exchange the LP fuel tank for a gasoline tank. On this particular 3010 LP utility tractor, some very brave soul cut off the LP safety relief valve and welded a gasoline filler neck to the LP tank, then drilled and tapped the bottom of the LP tank for a gasoline line (Photo 8). This is not a recommended practice for safety reasons. On two cylinder tractors, the liquid and vapor valve handles are usually mounted directly to the LP tank and will be removed with the LP tank. With a 3010 model tractor, the LP hood and gasoline hood are the same hood. With all other model tractors, you will need a gasoline hood to complete the changeover. With the gasoline tank plumbed to the fuel pump ( New Generation), and from the fuel pump to the gasoline carburetor which is attached to a gasoline intake manifold, all that is left is to install the gasoline hood and go to work. The LP to gasoline conversion on 4020s will require a different air intake tube from the air cleaner to the carburetor. The LP regulator on New Generation tractors can be left in place or removed and a gasoline/diesel water manifold installed.
Since New Generation LP tractors run at 9:1 compression ratio versus 7.5:1 for gasoline, you may notice some pre-ignition or pinging under load once you convert from LP to gasoline. To correct this, you can either run higher octane gasoline or retard the ignition timing a couple degrees. With New Generation tractors and many two cylinders, Deere used a taller piston to increase the compression ratio as seen with the dished gasoline piston in Photo 9 compared to the taller, domed piston in Photo 9. When converting from LP to gasoline, you should be able to measure a slight horsepower increase on a dynamometer if the LP pistons are left in the tractor.