Having fuel pouring out is a typical problem with most Q Jet carbs.The problem lies with either an improper set float or sticking needle which allows too much fuel into the bowl,causing it to overflow.I went through about 5 rebuilt Q Jets before I got a good one,but in the meantime I carried what I called "The GM carb Tune up Kit"with me a Small ball pein hammer and give the front of the carb a tap on the bowl,this usually loosened things up inside and back on the road we go.