I was reading the SACA Steam Automobile Bulletin November-December 2007. It concurs with Jeff's information. Arthur Eldridge who owns a 1901 Model O Lane writes: "I had a sizable lump of carbon in the valve body of my steam automatic.... The carbon problem has occured at the steam automatic... Like many early steamers the automatic was on the hot end of the vaporizer, thus controlling the fuel flow in a gaseous state. Most steam car makers moved the automatic to the inlet side of the vaporizer, thereby controlling the fuel in its liquid (state). This eliminated the problem of carbon in the automatic valve... I am now finding that current gasolines with ethanol are giving me little if any problems with carbon." The Steam Automobile Bulletin has a lot of useful vintage steam information in it. It is a better steam publication than it has ever been. Pat Farrell