I have a 1989 Thompson with a 4 cyl. 2bbl. Mercarb. I have had trouble with the engine flooding (gas runs down venturi after engine is stopped, leaves about 1/4" in bottom of intake manifold). I have read some of the postings and am going to check on the float setting, and rebuild the carb while I'm at it. Does anyone know how to tune in the carb when I'm done. There is only one idle screw, but I've never adjusted one before. Any suggestions would be appreciated. 