The 200 Mile-per-Gallon Carburetor: The Story of the California Carburetor
The carburetor in the illustration on the right was designed by Roy Marks. Granted US patent number 710,330 in 1902, it, together with number 710,329 (Explosive Engine for Motor Vehicles), covered all the major features of the “California Carburetor.”
Like many of the day, it worked on the “surface” principle; it was basically a box in which the fuel was allowed to form a vapour that could be mixed with air and fed to the engine. (Today, that vapor, when it forms in the gas tank, is burned using the evaporation control system).
Mark's carburetor differed from most by using cotton to draw the fuel up onto a series of shelves (through wicking action) to give a larger surface area for evaporation.
There was no float chamber; the rider had to open the tap every so often and add fuel to the appropriate level, judging by the level glass on the front of the tank. Tricky to do while riding! Still, in practice, with fuel consumption claimed to be close to 200 mpg, one fill would keep you going between stops.
The 200 mpg carburetor has been found. It is real. It was a popular technology when the automobile engine consisted as a large one or two cylinder engine that ran at a fixed speed, not much faster than 600 rpm.
Throttle control technology had not been created yet. Engine rpm was fixed by some form of governor applied to the sparking system (if any) or by holding a valve open when the rpm increased above a certain speed. Road speed was generally achieved by using two forward gears — one gear used for a fixed low speed and the second gear for a fixed higher speed. Very rarely did the high speed exceed 15 mph.
To build a 200 mpg carburetor for yourself [allpar does not recommend this], remove the lid from your air cleaner; remove the air filter, and fill the cavity with cotton cloth waste. Disconnect the fuel line from the carburetor and plumb it into the air cleaner using some form of a shut off valve similar to a toilet valve, [but capable of carrying fuel without damage]. When the fuel rises to a given level, it will be shut off.
As air passes by the gasoline-soaked rags, the fumes generated by evaporation would be sucked into the engine and the engine would run. Sort of, with a drivability problem or two, and the chance of a fire or explosion.
The carburetor butterflies would control the mixture into the engine, but not well. When you shut the engine off, the gasoline would still be evaporating; the fumes would be obvious. That could be solved. In the winter, you could route the hot exhaust gasses up to the air cleaner to encourage the evaporation to take place, and as long as you carried a fire extinguisher along and did not store the car indoors, there should be no real concern.
The oil companies did not buy this patent, as the urban myth goes. Why should they, it was hardly practical in the first place! It was used for a time, but automotive technology moved onwards and it was largely forgotten.