Found those tables for orafice sizes. Thanks Bobby M. i think. I live in the midwest. I clled my local gas supplier, they said that we run 7 to 7.5 in the winter time. ( don't know why the change ) Drilled up to .182 as per chart for my 100,000+ Bayou Classic. Viola, blue flame little yellow. Drilled 2, .250dia. holes in the back of venturi tube. ( make them different distances from center so you can rotate 180 to use propane again ) I think that I will need to drill the holes in the cast iron as big as .500 and file open the holes i made in the rotating restrictor plate th slots. It just seems to want more air flow. Inside with natural gas can fix any rainy day.