Big Four Tractor Restorations: A Global Endeavor

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The differential assembly from the 1910 Big Four tractor.
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This photo of a Big Four engine show the cylinders set in place and the water manifolds bolted on, confirming alignment and correct spacing between the cylinders.
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In the midst of the cylinder machining process for the 1910 Big Four.
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Aluminum piston castings for Big Four pistons in the background are flanked by finished pistons for another Big Four tractor, along with bearing caps and wrist pins.
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No detail is too small in refurbishing the 1910 Big Four, including foundry-made lugs for the wheels.
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When Al Severson needed to make the steering chain spring assembly for the Big Four, it required a lot of searching to find the correct spring to match the original. “I was able to obtain it from John Deere,” he says. “I told John Deere that at one time they marketed the Big Four, so they should have parts in stock.”
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Like almost everything on the Big Four, this steering assembly is double-nutted.
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Al made most of the parts for his Big Four, but he bought this Bennett carburetor, said to be a new old stock carburetor. “I have to believe that to be correct,” he says. “There are no signs of wear in any of the holes and all the detents look to be new. It is complete with the water injection.”
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A pattern had to be made for the differential drive gear for the 1910 Big Four tractor, which was equipped with three speed options. Al chose a low speed to match the original differential gear. To make the pattern, he used medium-density fibreboard in 3/4-inch sheets. He cut the sheets into circles, glued and screwed them together to make a 5-inch part, then used a lathe to true the pattern. A rotary table was used to index the gear for the tooth cutting. This is the finished pattern ready for the foundry.
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A restored Big Four on display at the Little Log House show, Hastings, Minn. A restored Big Four is a spectacle, Al says. “It looks like a?carnival coming to town,” he says. “It’s a very? ornate tractor.
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An original Big Four dealer sign from Al’s collection.
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Al’s second Big Four, a 1908 model. “We set the backlash in the pinion gears and removed the rear wheels so it was at a good work height,” Al says. “We set the engine we had been working on for our tractor and the transmission that Bruce Flatmoe had built for this tractor on the frame. The backlash between the transmission and the differential were then set and we are working on crankshaft to transmission shaft.”
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Al made a copy of an original wench for the threaded cover for the intake valve chest, shown here before drilling and threading the spark plug hole.
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Not only do the parts for the engine and transmission have to be made, so do fixtures to make those items. This piece allows Al to mount connecting rods in either a vertical or horizontal position for machining.
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One of the first purchases Morris Blomgren made, at considerable expense, for his Big Four tractor was master pinions. Here, Al remachines them for casting of new ones.
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Recently poured connecting rods and caps for a Big Four engine.
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A colorized photo of a Big Four threshing in an Indiana field.
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A colorized card showing a Big Four plowing in a field near Beach, N.D.

Ever wondered how to define the phrase “mind boggling”? Just ask Al Severson. The Blooming Prairie, Minn., machinist is juggling the restoration of not one but 11 Big Four tractors.

Fortunately for Al’s mental health, only two Big Four tractors (both of which are his) are physically present in his shop. The rest are scattered across the globe, but the Internet has brought them close together. When Al documented the experience of restoring a Big Four and posted it online at Smokstak, owners of the rare prairie tractors started coming out of the woodwork … and they all needed parts and information.

In addition to his own pair, Al is involved with restoration of four Big Four tractors in the U.S., three in Australia and one each in South Africa and the Netherlands. “All I send to owners overseas is information,” he says, “typically sketches or prints of different parts of the tractor, because I don’t want to deal with customs and all that. It works both ways. I help them out; they help me out with information, too.”

The group of 11 enthusiasts on four continents is tight-knit; members freely share information and parts. “It has truly become a worldwide group,” Al says. “If one person has a part you need and we have a part they need, we work together and everybody is satisfied. We end up being the central point for most of the parts being made for the Big Fours in the U.S.” Some need only minor parts; others require complete engine and transmission rebuilds — but he is up to speed on all of them.

The Big Four, a member of the class known as prairie tractors, is a rare tractor; just 25 are known to exist. The Big Four was built by Gas Traction Co., Minneapolis, until 1912, when Emerson-Brantingham Co., Rockford, Ill., bought out Gas Traction. Emerson-Brantingham continued to build the Big Four for several years.

An unexpected acquisition

Al’s involvement with Big Four tractors was a natural outgrowth of a lifelong hobby. “I grew up on a farm and my dad had a repair shop, so I’ve been working on tractors since I was about 6 years old,” Al says. “I’ve always had an interest in old iron, buying tractors out of the woods, fixing and reselling them to make a few bucks.”

In 1995 he rebuilt a Big Four engine for a show tractor at the Little Log House show in Hastings, Minn. “So I’ve had previous experience with the Big Four tractor and because of that it’s become a love of mine,” Al admits. “But I never thought I would own one.”

That opportunity came in 2009, following the death of Morris Blomgren, Siren, Wis. In 1988 Morris, an inveterate collector of old machinery, heard that the Reynolds-Alberta Museum in Wetaskiwin, Alberta, Canada, was dispersing some of the tractors in its collection — including a Big Four 30-60 chassis dating to about 1910. During the Dust Bowl of the 1930s, the tractor’s engine had been pulled off to use in an irrigation setup; the engine eventually disappeared. Morris bought what was left of the Big Four for $5,900.

“Morris always dreamt of getting the Big Four in running order,” says his niece, Janet Freeman. Unable to find parts for a reasonable price, Morris made little progress on the project. “The chassis remained in his yard at the time of his death,” his niece says. But she and Morris’ nephew, Roland Blomgren, wanted to see the restoration goal fulfilled while keeping the tractor in the area. Steve Bauer of the Little Log House show suggested Al Severson, and in June 2010, Al bought the tractor from the Blomgren estate.

“It had a frame and four wheels and a differential,” Al says of the Blomgren Big Four tractor. “But it was missing the engine and transmission. We haven’t come up with any original documents to pinpoint the date the tractor was made, but this one (serial no. 1131) was built by Gas Traction Co., so it’s about a 1910 Big Four 30-60 edition.” The tractor has a 6-1/2-by-10-inch bore and stroke.

Starting from scratch

It’s one thing to restore a rare antique tractor, but altogether a different challenge to replicate an antique engine, building it from scratch. “We disassembled it completely, down to the bare frame,” Al says. “The sheet metal and radiator were useless. We did the usual work of sandblasting and painting the parts. Following that came more unusual and difficult steps: making new castings for the missing parts. We had taken a good share of one engine apart in the mid-1990s, and obtained an owner’s manual and three parts manuals, which were also helpful. Those, along with a lot of propaganda, I guess you’d call it, which actually breaks down and shows you that this was made this way and that way, were all a terrific help.”

To build an engine from scratch would seem to require a few basic parts: crankshafts, rods, pistons, cylinder heads, manifold. “But there’s an unbelievable number of parts,” Al says. “Oil pump, tappets, cam follower guides and the camshaft. And it’s all got to be right.”

So Al borrowed the Hastings Big Four tractor and, over two winters, tore apart that tractor’s engine (the same engine he’d rebuilt in the mid-1990s) and transmission to measure and copy parts. “We reverse-engineered, you might say,” he says. “We made patterns using original parts, or carved them out of wood, compensating for shrinkage during casting.”

Cylinder patterns from earlier had to be modified, and then the castings were made. “We cast a new upper and lower crankcase, with every part of the engine brand new: the crankshaft, pistons, connecting rods, cylinders, manifolds, every part in the engine,” Al says. “Every part of the transmission was also cast brand-new. The process was much more difficult than could have been anticipated.”

An education in casting

The cylinders were the worst, he says. “Once we had the patterns that had been built, there was a tremendous learning curve by the foundries,” he says. “One foundry made some good parts, but the ratio of good parts to bad was really high, so they told us they wouldn’t make any more for us.”

A second experienced foundry made better parts in general, but struggled with getting the cylinders right. “It was the complexity of it, with the water jackets and valve chambers and so on,” Al says. “There’s just so much that goes on in cylinders. This particular cylinder is a headless design, so the valves and head are part of the casting. That means a need for more cores and if anything moves or anything happens, you get a bad part. When you pour metal, gases build up and need an escape route, which is too often blowing a hole in the casting. So the cylinders were doubtless the hardest part.”

The huge size of the parts created another problem. The cylinders weighed 140 pounds each. The crankshaft weighed 200 pounds. The crankcase consisted of two parts weighing 400 pounds each. “Most of the castings used original Big Four gray cast material, but the crankshaft and some other parts were built of ductile cast, like modern auto crankshafts,” Al says. “The foundry said you couldn’t see any difference in the crankshaft until -30 degrees. When it’s that cold, we won’t start the tractor.”

A dynamic duo

Outside of the casting, everything else was done in house. Al and his wife, Harriet, poured their own babbitts, did all the machine processing, and so forth. Everything in the engine was made new with the exception of an original new old stock carburetor and a used governor.

The sheet metal was rusted and bent, usable only for patterns. “The only difficulty with the sheet iron is rolling angle iron around the perimeter of the fenders,” Al says. “Angle iron is difficult to roll.”

Sheet metal work is about all that remains to be done on Al’s 1910 Big Four. “It’s actually going together relatively fast,” Al says. “We made the radiator, the engine is sitting on the frame (though it’s not yet bolted down) and I put in the clutch, transmission levers and the steering linkage in December.”

Al says Harriet is a full partner in the undertaking. “She works in the shop with me,” he says. “In a production, I’ll make the first part and she’ll run the rest. She keeps the production work going so I can play with the tractor, and she goes along to the shows.”

A second Big Four

After collector Brett Kemper, Lincoln, Neb., died in the summer of 2013, Al went to the Nebraska man’s farm and sorted through the collection of parts for the Big Four tractor Kemper had been planning to restore. “I made a pile for the family,” Al says, “so everything would be together when they decided what they wanted to do.”

The family decided to sell it to Al, along with Bruce and Brian Flatmoe, Menno, S.D., who had been very helpful with Al’s other Big Four projects. “This one appears to be a very early one, as some castings on the tractor mean it had a rear thresher pulley, which makes it about a 1908 model,” Al says. “But it has no serial no. The company painted the serial nos. on the front of these tractors. Morris’s tractor was parked in the shade so the serial no. remained visible, but that’s not the case with this one.”

Keeping it all straight

The biggest challenge Al faces in his projects is time. “It’s already been three years since I started working on that 1910,” he says. “I don’t know where the time goes. But I do have my machining business and customers, too.” The project is also marked by a certain amount of monotony. “It’s a lot of fun to make one part,” Al notes, “but making parts for a bunch of tractors becomes production work. For example, each tractor has eight tappets, or valve lifters, in it, so for four engines, that’s 32. That gets kind of old after a while.”

Juggling the details of 11 simultaneous restorations — especially when most of those tractors are not on-site — also requires a certain mental dexterity. “We keep ledgers for each tractor,” Al explains. “We document all the parts that come into the shop, and who they’re for, the time it took to make them, and what was shipped and when.”

Days go by when Al sees no real progress. “You do some small things, but at the end of the day you don’t see that you really accomplished anything,” he says. “The most fun is when you see that you did something, like putting a big assembly on the tractor, or the transmission on the frame, or setting the engine on the frame for a mock line-up. Then you can see that you did something. Any time you see some advancement, that’s great.

“The plan is to get (his circa 1910 Big Four) done and take it to a bunch of shows and have fun with it,” Al says. “Maybe in another year or so. It’s not for sale. I tell people that overall my goal is to make the most complex estate that I can for my kids.”

People react with total amazement when they hear about the project. “Some are shocked that this can even be done,” Al says. “Many people appreciate what I’m doing, but are amazed at the magnitude of it, making not just a part or two but a complete engine.” He’s the first to admit it’s a singularly challenging undertaking. “But it’s the only way I can afford one,” he says. “These prairie tractors sell at incredible prices, like the $375,000 Flour City that sold at the Ertl sale to $600,000 for some rarer one.”

People in the hobby make it all worthwhile, he says. “A project this size needs a lot of brainstorming from anybody with information. I’m helping them and they’re helping me. Everybody wins,” he says. “It’s created a camaraderie, so together we’re happy. It’s unbelievable how many nice people I’ve met through this. That’s probably the biggest thing of all, all the friends that you make. And when we’re done, there will be 25 Big Fours running across the world.” FC

Workhorse of The Prairie

Big Four tractors were instrumental in breaking the prairie sod from Kansas to Canada, but they weren’t very useful on a small farm. After the sod had been broken, the most likely place to find a Big Four was the huge Bonanza Farms of the Red River Valley between Minnesota and North Dakota.

Al Severson’s circa 1910 Big Four was used in a huge Canadian threshing operation. “Those big tractors did the basic minimum tillage, plowing, digging, dragging and planting in one operation on big farms of 5,000 acres or so,” he says.

The Big Four was touted as the best of its type on the market at the time. “I see some weak points, which were probably not the best,” Al says. “The main journal of the crankshaft was 2-3/4 inches in diameter, while the competition had crankshafts of 4-5 inches. I’ve got to think there was some bearing trouble in these machines, but beyond that, they were well-designed tractors.”

Read more on Big Four tractors in Gas Traction Co. Designs 4-Cylinder Tractor.

For more information contact:

– Al Severson, 10374 Bixby Lane, Blooming Prairie, MN 55917; email: or

Bill Vossler is a freelance writer and author of several books on antique farm tractors and toys. Contact him at Box 372, 400 Caroline Ln., Rockville, MN 56369; email:

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