In 1969, Jon Kinzenbaw was a talented welder and fabricator in Ladora, Iowa, whose reputation for being able to design and fabricate just about anything was expanding rapidly. With a farming background and a natural engineer’s mind, he had already invented and was producing machinery to make farming work easier. When a local farmer approached him to repower a John Deere 5020, Kinzenbaw created another new product that would further establish him as a mover and shaker in the ag world.
The big Jimmy-powered Deere smokes noisily into the cold, fall air of northwest Ohio and dreams of the glory days. It’s still a viable tillage tractor so those glory days are not necessarily over. Life as a pulling tractor is also possible.
Jon’s early business model included handling pretty much anything that came in the door. That philosophy was modified over the years but it included the repowers, and as long as they remained popular and sought after, they remained in production. Kinze Manufacturing initially focused on the 5010 and 5020, 4520, 4020 and even the 6030. Most were fitted with Detroit 8V71s, but a few used 6V71s. Kinze’s records show 200 kits of all kinds were built.
Many of the repowers were performed in-house but a number were sold for conversion elsewhere. This phase of the repower biz faded away after 1976 due to declining demand but it picked up again in the ’80s with repowers for the big articulated Deeres like the 8630 and 8640. No Jimmies this time… the 833 Cummins was the powerplant of choice.
By no means is Kinze Manufacturing known only, or even mostly, for their tractor repowers. Their tillage equipment, fertilizer applicators, grain carts, augers and planters are highly regarded to this day, and the Kinzenbaw heritage of innovation continues. Kinze now operates out of a million square-foot building in Williamsburg, Iowa, and sells product all over the world. Kinze hasn’t been offering repowers or repower kits since 2007 but their discontinuation announcement pledged to continue parts support.
With no mufflers, the Detroit is eardrum-splitting loud… even at a fast idle. With mufflers, the noise is merely uncomfortable. Without mufflers, it’s agonizing. Hearing protection is a requirement for the operators of any of the Kinze Detroit repowers.
One of the most common questions about the early days is, “Why the Screamin’ Jimmies?” It was a combination of dimensions and power output. The V-8s replaced the inlines without completely reengineering the tractor. The larger, more powerful sixes of the era would have taken much more adaptation. The V-8s also developed a substantial 300 hp, more than double the best of the six-cylinder engines they replaced… and the Detroit was a proven design. Yeah, it was a loud sucker, and it had a drinking habit, but it could send you down the rows in fifth gear at 10 mph with an implement that previously had the tractor grunting along at 3 mph in second gear. The other side of that coin is being able to run larger implements at slower speeds.
Another question that comes to mind is how the J.D. final drives held up. Quite well, as it turns out. The tractors that formed the core of Kinze’s conversion market in the ’70s came from an era when Deere was fresh from its transition from two cylinders to inline engines. The two-cylinders required a beefy final drive so J.D. tended to build extra strong anyway, but their transition to inlines made them even more careful so as not to do an embarrassing technical faceplant. A few minor mods were made to the final drives as needed.
The 6V71 debuted in 1957 along with its big brother, the 8V71. In case you didn’t know, the engine designations broke down like this: 6 = number of cylinders, V = cylinder configuration (no letter = inline), 71 = displacement of the cylinder. The bore and stroke were modular… 71 cubic inches per cylinder, whatever the arrangement or number. The only variable was the number of cylinders. Debuting in 1938 from the Detroit Diesel Division of General Motors, over the years the two-stroke 71 series was offered one-, two-, three-, four- and six-cylinder inline engines as well as V-type engines with six, eight, 12, 16 and 24 cylinders. The 6V71 was a popular engine for rear engine transit busses. Detroit Diesel finally discontinued manufacturing two-strokes of all types in 1998 when it became impossible to get them emissions certified. Some 3.5 million two-stroke Detroits were built from 1940 on and, reputedly, at least 500,000 are still in service.
While the 8V71 powerplant formed the core of the 200 kits Kinze offered, the company remembers a handful of 6V71s being built. The kit was very similar since the engines were. This brings us to the focus of this story, Paul Merriman and his Kinze repowered 4520. It’s a ’69 that was repowered with a 6V71 in the early 1970s. That was unusual for Kinze. According to Mike Dykstra at Kinze, who handles many historical enquiries about the company, very few 6V71 conversions were done, making Merriman’s a rare bird.
The 71 series, as well as the 51, 53, 92, 110 and 149 series, was a scavenged uniflow engine, meaning it uses intake ports in the cylinder walls rather than intake valves. When the piston reaches the bottom of its stroke, the ports are uncovered and a Roots-style compressor pushes air into the cylinder. The air comes at not much more than atmospheric pressure, so the engine isn’t “supercharged,” even though the GM compressors have been used as superchargers. In later years, a turbocharger was added to the two-stroke Detroits which boosted the intake air volume above atmospheric. This boosted power also cleaned up the notorious smoky Detroits a little.
Paul has researched his tractor, which he bought from a local NW Ohio farmer in 2004, but only learned a few tidbits about the tractor’s past lives. It was in rough shape, having been sitting inoperable outdoors since the mid-1980s. With injectors, batteries, fuel lines and a host of other little repairs, he got it running and operating. It’s showing 4171 hours and it’s unclear how many of those are with the Jimmy, nor how many hours were on the engine when it was installed. It’s an ongoing project that will eventually get a full restoration. Maybe even a swap to a more powerful 6V92.
The inline six and V6 71 series engines were rated for identical power outputs. With both engines, output varied according to application. They are commonly seen in the 190-240 hp range. The later 6V71T had a turbocharger and produced up to 274 flywheel hp at 2,100 rpm and 742 ft-lb at 1,400 rpm. The 6V71 engine weighed a hefty 2,010 pounds, and to adapt the engine, Kinze needed to build frame rails. The air filter is a monstrous unit from Farr. Kinze tried several different types and locations for air filters in the early days and finally settled on the Farr. It was highly efficient and didn’t block forward vision but required hood modifications. The downside was that the filter tended to draw a lot of hot air from the exhaust manifolds. Speaking of those, they are unique to Kinze.
Though tired, Merriam’s tractor can still pull a nine-shank chisel plow or a 5-16 moldboard plow in sixth gear with contemptuous ease. When hooked up to a dyno, it delivered 210 hp on the PTO. A new 426-cid 6V71 for road use was tuned for 238 hp at the flywheel and ag applications were often tuned lower. A 210 hp reading on the PTO is a pretty good number for a tired engine that sat for nearly 20 years. Several sources list 210 PTO hp as a common setting for 6V71s in tractor applications. The original JD 404-cid engine delivered 123 hp to the PTO.
While time has not been kind to Merriman’s tractor it, like many others, will eventually get the clock to run backwards and live a new life as a collectible tractor. Kinze repowers of the ’70s are getting collectible in their own right and are still useful to those who need them.
From the pilot station, a Kinze conversion was just like a Deere except that you had “stereo” from the twin stacks. All the controls were the same. That the final drive could take the added power is a testament to John Deere engineering. Apparently both Synchro-Range and Power-Shift final drives were converted.
By Jim Allen
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