Since alcohol is usually cleaner burning than white gas (petrol) it might be attractive to convert your liquid fuel stove so it is able to burn alcohol. There are 2 ways you can achieve this. Enlarging the bore of the jet or narrowing the holes for air intake. Both have the result that the air to fuel ratio is lowered. Alcohol (C₂H₆O) requires less oxygen from the air to burn than white gas (C5-C8). When too much air enters the stove the flame will be blown out. When there is a lack of air intake the flame will turn into orange instead of bright blue.
A comprehensive explanation on how to convert a MSR Whisperlight to a stove that is also able to burn alcohol was done by Electric Trike. This adjustable air inlet restriction makes it possible to burn white gas and alcohol without modifying the stove back and forward. Also the amount of air can be precisely adjusted to obtain the right flame.
Some examples of liquid fuel stoves that can be modified to burn alcohol are the MSR Simmerlite, Sigg Fire-Jet and Optimus 111T. The last one came with original manufactured jets and a air restrictor to burn White gas, Kerosene and Alcohol.
The Optimus 111 stoves with a silent burner came with a factory made air restrictor and a special alcohol fuel jet (spare part #2508) was available. BernieDawg has made a video demonstration about how this works and how you can do this yourself.
Also the Optimus 207 adjustable silent burner and similar models could be modified from Kerosene burners into Alcohol burners. Besides the alcohol nozzle part 2508 you need to install a air restriction tube. This can be made from standard 12 mm outer diameter brass tubing from the hardware store. The sideward drilled hole can be drilled wider a few times. A too small hole will lead to a lack of oxygen and therefore a yellow flame. A took large hole will lead to too much air intake and the flame will be blown out. Besides this it is usually also necessary to install a flow restriction inside the burner under the nozzle. A piece of gauze or metal sponge will regulate the fuel supply. Without this there is a change of fuel build up inside the tube under the nozzle. This will evaporate vigorously every now and then and cause the flame to flare up and down. The result is then a flame that can be blown out completely and or that too much fuel reaches the top of the burner without evaporating into a gas.
