Here is a Burner Head and Body ready to assemble. All that needs to be done is to screw the Head onto the Body till the inside top of the Head is about 0.050 from the end of the tube. This dimension isn't critical, and I just eye ball it. But as a rule of thumb the further away it is, the lower the pressure will be where the flame jumps from the head. At 0.050 these will usually run all the way up to 15 PSI. I stick the same piece of CRS through the air mixture holes and use it to hold the body while I screw the head on with a wrench.