So if the slide is all the way up at wide open, the smallest diameter is inside the needle jet making for the largest opening. Vice versa when the slide is all of the way down. Some needles have adjustable height positions while sitting in the slide. An E-clip sets the position, and that position is often referred to as “the clip.” Moving the clip up will lower the needle, making it leaner. When there are no clip positions on the needle, you can move the needle up by placing small washers (a move called shimming) in between the needle and slide. To lower the needle? You will need a longer needle.