D-400 engine
{{Infobox automobile engine
| name = D-400 series engine
| image = Masport Iron Horse Mower.jpg
| caption = Restored Masport Iron Horse engine
| manufacturer = Outboard Marine Corporation (OMC)
Lawn-Boy
| aka = Iron Horse
| production = 1954--1977
| predecessor =
| successor = D-600
| configuration = Single-cylinder 2-stroke
| displacement = {{convert|108.99|cc|cuin|abbr=on}}{{Cite web|url=https://lookup3.toro.com/ttcGateway/acrobat/manuals/lball.html|title=Lawn-Boy Service Manual 1950--1983|accessdate=2012-02-04|year=1983|author=Lawn-Boy}}
| bore = {{convert|60.325|mm|in|abbr=on}}
| stroke = {{convert|38.1|mm|in|abbr=on}}
| block = Aluminum
| head = Aluminum
| valvetrain =
| compression = 4.5:1
| supercharger =
| turbocharger =
| fuelsystem = Float carburetor
| management =
| fueltype = Petrol
| oilsystem = 16:1-32:1 pre-mixed fuel:oil mix
| coolingsystem = Air-cooled
| power = {{convert|3.5|hp|kW|abbr=on}}
| specpower =
| torque =
| length =
| width =
| height =
| diameter =
| weight =
}}
The D-400 series engine or the Iron Horse engine was a light-duty two-stroke engine used for powering lawnmowers produced from the 1950s to the late 1970s. D-400 engines were single-cylinder engines designed and manufactured by the Outboard Marine Corporation (OMC; Johnson and Evinrude) for Lawn-Boy{{Cite web|url=http://www.lawnboy.com/about/history/index.html |title=Lawn-Boy brand history |accessdate=2012-02-04 |year=2012 |url-status=dead |archiveurl=https://web.archive.org/web/20120213165600/http://www.lawnboy.com/about/history/index.html |archivedate=2012-02-13 }} and Masport. The D-400 engines displaced 109 cc, generated {{convert|3.5|hp|kW|abbr=on}} of power, and operated in the range of 2400-3300 RPM.{{Cite web|url=http://forums2.gardenweb.com/forums/load/lmower/msg0403314716766.html|title=Lawn Boy Engine series|accessdate=2012-02-04|year=2008}}
Description
The engines have a distinctive rectangular cowling that has created a nickname of brick-top mowers. Another distinctive feature is the two-finger vertical recoil starter. The kidney-shaped muffler and exhaust unit is mounted beneath the mowers' deck and gives the engine a small, low profile design when compared to the newer and more powerful lawnmower engines. The ignition system employs a magneto, points, and a condenser (capacitor) set-up with an unusual spark-advance system which utilised a weight on the crankshaft to adjust the spark-advance amount depending on engine speed. The sprung governor was also unusual with a throw-yoke which operated under the flywheel and was linked to the throttle. The carburetor was a float design and fed into a pair of reed valves.
In New Zealand and Australia, Masport also known in New Zealand as "Charlie Gamble" offered the D-400 engine on their Premier, Premier II, Rancher, Rotacut, and Tornado models.{{Cite web|url=https://www.youtube.com/watch?v=7sH3LfMZmnc|title=Moving Up to Masport TV {{sic|nolink=y|Commercial}} (1972)|accessdate=2012-02-04|year=2011}} In this Oceania market, the D-400 was called the Iron Horse engine.
References
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