A long time dormant this thread but here are a few thoughts on kerosene, petrol and diesel.
from my experience with these fuels in a full size Stanley steam car.
Petrol was, in the early 1900’s, almost a waste product of the lighting oil industry in the USA and very cheap until petrol engined cars became so successful. Most early steam cars ran on petrol until about 1914 when petrol became more expensive than kerosene. Stanley then modified their main burner to run on kerosene although they stuck to petrol for the pilot.
Nowadays most steam car owners with vaporising burners use a mixture of 50/50 petrol/diesel because it is available everywhere, unlike kerosene. Because both fuels are intended to work in a very sophisticated i.c. engine, be it petrol or diesel, they have to be very closely specified. The product is therefore consistent and one can fiddle with the proportions and the length of the vaporiser pipe to get good vaporisation without overheating the mix and making loads of carbon. Kerosene and 28 second central heating oil might be expected to work but because neither is intended for use in a situation where volatility is critical, it seems that the product sold is very variable - some would say any old rubbish!
So the main burner is generally fired on the 50/50 mix. The pilot does not like the mixture or straight kerosene as the normal vaporiser is too small for the heavier fuel. In fact even current petrol creates a problem because in the cold air around the front of the burner the vaporised fuel condenses before getting to where it is supposed to burn - the pilot being of the silent burner type as illustrated by Westbury and others. The reason being that petrol contains a rather wide variety of long chain hydrocarbons, with boiling points ranging from 40C up to even 200C. Unless the gas can be kept above about 90c, some will condense, leading to a reduced flow of induced air, a yellow flame and a vicious spiral as the vaporiser cools and the flame goes out. The answer to this for some is to use hexane instead of petrol as, being one compound, it boils at a consistant 69C. It is though highly inflammable, hard to buy and risky to store at home.
There is however another more closely specified kerosene (Jet 1) which has to work in jet engines which are in fact just monster vaporising burners with a few blades added. I have no experience of Jet 1 but there is every reason to think that it would work well in a steam car or in a model kerosene burner. I say this having heard that a friend, given the task of making the BRM Rover gas turbine racing car work after many years disuse made the mistake of trying it on ordinary kerosene which was quite hopeless, burning yellow and cause all kinds of problems which disappeared immediately once it was fed with Jet 1.
There were kerosene after-market pilot lights supplied for steam cars in the 20’s and the problem is mainly that of adding the just right amount of vaporising heat, adjusting the vaporiser length, its position in relation to the flame, and getting the proper air flow. With ordinary kerosene this might be tricky, but I reckon that with Jet 1 the job could be made much easier.
Just my thoughts
Another Mike