Carb Fuel/Air Mixture Screw Q.

I intalled a back-up carb (single barrel) this afternoon and the engine appears to be running fine, but while adjusting the fuel/air mixture screw, I turned it all the way in and it did "not" stall or kill the engine. What is the normal problem when this happens??? Is it the furel/air mixture screw that is normally worn; or what??? Thanks, Jim

8) its possible that the mixture screw has a groove in it, or that the idle speed is a bit high meaning that the engine is running on the transition slot, or the idle mixture opening has been enlarged, or there is an internal leak in the carb.

Rbohm, thanks for your comments. Since I posted, I installed a different fuel/air misture screw from a different carburetor (that is functioning normally) and the carb would still not stall or die when I turned that 'new' screw in as well. Even though I did not hook up my dwell/rpm gauge, I barely had the idle mixture screw keeping the engine running; so I am guessing that the rpm's were probably 500 to 600rpm. As far as an internal leak, that is always a possibility. I plan on rebuilding this particular carb, so I will see how she performs after the rebuild. Thanks for your input. James