The above illustration should serve as a guide in a step-by-step process in assembling a basic oil lamp. If you purchased your kerosene lamp complete, then all of the parts should assemble without having to bother with measuring for correct fit between components.
1.) Determine the collar size of your lamp. Most collar sizes were standardized during the kerosene era. The collar size of your lamp will, of course, determine the correct size of kerosene burner to use on your lamp. Click this link for a full explanation collar & burner sizes:
How To Replace a Kerosene Burner
2.) After having obtained the correct kerosene burner (make sure the wick is proper inserted and that the wick winder functions properly) you may now attach the burner to the lamp.
All of Antique Lamp Supply’s burners are tested with antique and modern lamps to insure compatibility, but all lamp collars are a little different and some old (and new) lamps may have damaged threads inside the lamp collar.
Attach the burner to the lamp (collar) by slowly turning the burner in a clock-wise manner while lightly and evenly pressing down. The mounting procedure will tell you whether or not the burner is a good fit. A good burner-to-collar fit will be characterized by smoothly turning threads and a snug fit when the base of the burner threads fully into the top of the collar.
3.) Mount the chimney by slipping its base inside the springy tines that rise above the burner. Try to apply light pressure to the tines as the chimney goes down so that the chimney will be held in center of the burner. If the tines are bent, lightly bend them back to perpendicular so that all 4 tines apply equal pressure on the chimney base.
Click this link for more information on selecting and mounting kerosene lamp chimney glass: