Back in the early 1950's, Dad used a big Zenith 2-barrel carb designed for a gasoline engine Mack truck on a flathead Ford dirt track engine. That carb had removable venturis, which he put in a lathe and bored out until the restriction was barely there, just enough to develop a little vacuum to pull the fuel from the float bowl. Then he drilled out the main jets to the point they would break off if they were tightened too much. Why all this modifying? He was running a mixture of alcohol and Hydrogen Peroxide as fuel, and the engine needed a LOT of it to run right. 8 laps per gallon on a 1/4 mile track was about average, running a 300 cubic inch engine. That single carb routinely outran competitors running three Stromberg 97 2 barrels. All the mixture tuning was done on a chassis dyno owned by one of his sponsors, one that was normally used for road tractors. Mixture adjustments were done by changing the high speed air bleeds, meaning that to get a richer mixture, a smaller air bleed was used.
Jerry
