Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

The first reference I grabbed turned out to be for my Clevedon Steam boiler which says "....to ensure the gas burns efficiently, gently slide the gas jet holder in or out of the burner mixer tube until a steady, quiet sound is heard. If there is a guttering noise or a whistling, the holder is too far out; too far in and the burn will be too rich. This will be noted as a sickly and overpowering smell of gas." Hope this helps you.