Hot Tube Ignition

This is my first time writing anything on one of these pages.For many years I pumped crude oil up here in northern Ohio using S.M.Jones engines with hot tubes on powers. The length of the tube is critical,longer tube for advanced firing and shorter for retarded timing.Another thing to consider is the RPM's desired out of your engine.Sometimes in stripping these old wells,I wanted to run the engines slow.An even shorter tube was needed. When running at a higher RPM, say 250, a longer tube is used so the timing occures enough before top center for optimum performance without knocking.Yet if the same engine is slowed down, using the same tube, it will knock considerably because more time is available between the firing of the charge and top dead center.My suggestion is to experiment with length of tube at the desired RPM's you wish to operate your engine.Also,the hot tube chimney needs to be lined with some type of insulation to reduce heat transfer and keep the tube red without damaging it.Many a nickel tube has been ruined because of too harsh a gas flame, the inexperienced operator trying to keep his engines tube red hot without insulating between the tube and chimney.I am out of room. If anyone is further interested,let me know and I'll ramble more on these subjects.