Custom FAST EFI offers modern performance for classic tractors
By Brandon Flannery
Farmers have long been admired for their ingenuity. When 75-year-old David J. Kepner wanted his vintage John Deere tractor to run as well as his pickup, he wondered why he couldn’t use fuel injection. After devising a solution, the retired John Deere mechanic worked with the staff at Fuel Air Spark Technology (FAST) to make it happen — with impressive results.
John Deere entered the tractor market in 1918 and found immense popularity with their two-cylinder tractors. The “New Generation of Power” from 1960 to 1972 brought modern four- and six-cylinder tractors into the ranks with a giant product showcase event, five years in the making, in Dallas, Texas. Though factory-rated at 80 HP, event test results for the six-cylinder 4010 produced 84 HP, making it one of the most powerful two-wheel drive farm tractors of the day. With more horsepower, easier operation and conveniently located controls, the “New Generation” series sold more than 184,000 units and made John Deere an industry leader. The 4010 was upgraded to a 4020 in 1964.
Kepner says the 4020 diesel is the best tractor ever built, and suspects Deere intentionally kept the power of the gas models slightly lower to sell more diesels. However, he happened to have a 4020 gas engine in his shop and decided to see if he could make it run better with EFI. In need of a tractor to hold it, he found an engine-less 3000 series on the way to the recycler and bought it for scrap price.
John Deere fans will know that the 3000 series runs two cylinders less than the 4000, so room had to be made to fit the inline six. The frame was stretched 12 inches and a custom hood was fabricated, resulting in a “long and lean” tractor that turns heads.
Spacers were made to move the intake manifold five inches out from the head and separate it from the exhaust manifold. This allowed room to add bungs for the fuel rails. The jet assembly was removed from the top of a 2.5L GM Iron Duke throttle body and inverted onto the intake flange.
With a displacement of 341c.i., the questions were answered on the FAST EZ 2.0 hand-held touch screen, and a tune was configured to work with six injectors that spray directly into the manifold ports. They use a mechanical pressure regulator set at 43 lbs. An air/fuel ratio of 14:1 was found to be optimal without allowing the engine to suck in too much air when slowing down. The throttle shaft was extended to match the five-inch manifold spacing and keeps everything working like stock, including the governor.
After 50 years, the tractor’s fuel tank was deemed too rusty and contaminated for service. It was replaced with a 29-gallon polyurethane tank. With some fine-tuning for max output, the new setup dynoed at a whopping 120 HP. Kepner says he dialed it down to a more practical 100 that still retains a very noticeable increase in performance and power.
He feels the system’s ability to efficiently burn ethanol is one of the leading benefits. The 4020 was designed to run on regular gasoline, and the updraft carburetor system wasn’t as effective with the modern introduction of ethanol into the mix. The closeness of the injectors to the intake ports and correct metering of air offer far better fuel efficiency over stock. He says it starts right up in freezing weather, without smoking or running rough.
As word spread, other owners asked Kepner to convert their tractors over. He put together a little “kit” including a manifold he has made and has upgraded more than a half-dozen tractors. He’s also begun selling them to “rural repair” shops at jobber prices so owners can have their local repair guys do the installation. He also runs the fuel rail on the bottom side of the intake, away from the exhaust manifold, and recommends an electric fan to keep the cooling system’s temperatures more precisely controlled. The fuel rail is on the top side of his intake for display purposes at shows.
If you’d like to discuss the conversion with him or want any more information, he can be reached at: D.J. Update ℅: David J. Kepner, 27724 Wyanet-Walnut Rd, Walnut, IL, 61376 or by phone at: (815) 303-5660.