Deere 400 goes “Hmmmmmmmmm”.


Some of you are probably old enough to remember the old Mazda car commercials from the 1970s and ’80s. At that time, Mazda was using smooth and quiet, though not very fuel efficient, Wankel rotary engines in its cars and the little jingle in the commercials said, “Piston engine goes boing, boing, boing boing, boing, boing, boing but the Mazda goes hmmmmmmmmm.”

Bill Schwab of Cincinnati, Ohio saw one of these rotary engines sitting at a swap meet one day and thought to himself that it might look good sitting in a John Deere lawn and garden tractor. It’s not like this was a revolutionary idea for Bill. He had already successfully transplanted a Craftsman V-Twin engine into a 212 and Geo Metro three cylinder and Pontiac “Iron Duke” four cylinder engines into 300 series tractors. And he has the skills to do it, having worked at the family’s welding and fabrication shop for 58 years.

For the Mazda engine, though, Bill felt that he would need a little more room than the 300 series could offer, so he found a model 400 with a bad engine. It was still a tight fit and probably the most difficult part of the job. The engine had to be high enough to clear the steering shaft, low enough to clear the hood and back enough to allow room for a radiator.

When Bill bought the engine, it was still attached to the original four-speed transmission. Since the starter was bolted to the clutch housing, and the clutch housing was part of the transmission, the two had to be cut apart.

Because of the way the 400’s original Kohler engine sat in the tractor, the Mazda engine now ran the hydrostat backwards. This, in turn, made the tractor’s hydrostat lever work backwards, having to push it forward for reverse and back for forward. To solve this problem, a jackshaft was built into the linkage and the lever now worked as it did originally.

The spec sheet for a Mazda RX-2 (which is probably what the engine was originally installed in) listed it as having 97 horsepower. The turbo charger was not original equipment on the Mazda rotary engine, but was added sometime between when the car left the factory and when Bill bought the engine. How many horsepower it would add is unknown, and isn’t really important, because Bill never runs the engine at high enough RPM to create enough boost to have an effect. To do so would ruin the hydrostat in short order.

Bill Schwab doesn’t know what his next project will be, but he has several ideas. Part of the fun of it for him is finding the needed parts without spending too much. He has collected a Triumph Spitfire engine, a flat head Kohler four cylinder engine and has considered an all electric articulated tractor. Of that list, only the last one will “hmmmm” any quieter than the 400 rotary.

If you would like to see that old Mazda “boing boing” commercial.