Hi Gordon, one of my long term projects is a 1 1/2" scale steam roller to the Bill Harris design. Pic of the plan book cover is attached. This design was covered in a series in Live Steam magazine years ago. The general design is simple but I have had some problems getting the boiler tubes to seal - many attempts but no joy yet. I also carved my cylinders from solid rather than buy Stuart castings as the design called for. Locally suppliers wanted a fortune for the castings, which I could not afford. This design might be worth a look.
The Harris design was originally intended to use "canned heat" Sterno fuel but I changed this to a 4 head "Marty" burner for propane. My idea was to haul a trailer with a small propane cylinder disguised as a water wagon. The "Marty" burners are documented on the Golden Gate Live Steamers website in the engiineering section. They burn well but time will tell as to whether they deal well with the low crownsheet in the Harris design boiler. If I can't get the tubes to seal in my boiler I will be doing a new boiler with a) more watertight construction, all silver soldered b) a higher crownsheet and wet wall firebox. We shall see.
