One of the best engine conversions is a Chevy 250 into a Land Rover Series. I decide to install a Weber 38/38 carb. “Same setup as the 6=8 from Clifford Performance.” However I do not get the jetting right. The engine idles and accelerates rough. Spark plugs burns dry black color. Sign of richness in fuel. This is a newly build engine. I have done all the leak testing. New plugs, cords and electronic timing. Please, if anyone is running the Weber 38 successfully on the 250 Chevy send me the jet sizes and timing degree you are running.