"Dilworth remembers with a wry grimace the 5-year struggle to create a distillate burner. He doesn't consider the campaign a success, though out of it arose certain benefits that have been of permanent value to the railroad business.
"First of all, Dilworth had to discover what a distillate was. About the best definition he could arrive at was that it was anything that didn't really classify as heavy fuel oil. It might range from a low-grade gasoline, to painter's naphtha, to gas oil. In fact it was anything the refinery didn't happen to want at that particular time.
"The most uniform product Dilworth came across was something known as Dubbs oil, the heavy half of the pressure benzine taken off during the Dubbs cracking process. Attempting to burn this stuff in a carburetor engine, according to Dilworth, was grim business.
"'In order to mix Dubbs oil with air and get it safely into the cylinder, we had to have a carburetor on each pair of cylinders,' Dilworth recalls, 'and these carburetors were fearful and wonderful things. On our largest model we even converted the intake valve of each cylinder into a carburetor, so that the mixture could be introduced into the cylinder practically at once.'
"Burning the stuff after it got into the cylinder was like 'trying to set fire to a wet haystack.' The designers had to put four spark plugs in each cylinder head. Where a gasoline engine would fire with one spark plug carrying about 35 milliamperes at 10,000 volts, the four spark plugs of the distillate engine each delivered 70 milliamperes at 20,000 volts." *
* Reck, F.M. (1954). The Dilworth Story. (p.38). NY: McGraw Hill.
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