Here is a link to an article written before the flight. I contains some nice (general) details about the fuel, engine, carb and modifications.
http://news.nationalgeographic.com/n...satlantic.html

"Fuel consumption is a tricky issue. Hill must set the rate of fuel consumption by trickling a "whiskey shot," or two ounces of fuel an hour, through a small hole that can change size because of temperature or humidity. If the plane uses too much fuel per hour, the engine will run fine, but they will run out of fuel. If it uses too little, the engine can stall out, and if it does the plane will crash. "