While you have it apart, blow out all the passages and run thin wires thru where you can. The metering block is sealed, so air is about all you have to use. Blow in reverse direction from the normal flow. My Holley 1920's ran terribly until the last one, despite my attempts at rebuild, but I didn't have an air compressor then and just followed the instructions in the kit. I never saw any dirt or debris in the carbs, yet they all idled lean until the last one.