cut off

[kiwi Rob]

As a new comer with a lot to learn ,I have this question , which bothers me a little , I read somewhere that the valve events used in the Stanley record breaker , were appropriate for use in a boat , but had also been advised that unlike a car , which could adjust its engine ( cut off) to match the road conditions , but a boat was like a car going up hill in third gear the whole time and that steam always needed to be admitted to the cylinder for most of the stroke .. I need a lot of help as you can see ... Rob

[fredrosse]

Cutoff at 50-60% of stroke will give better steam economy, and that would be the typocal cutoff values for an economic design. Running the engine with cutoff at a greater percentage of stroke will give a little more power, but will use much more steam. Most steam valve gear allows the operator to select some variation in cutoff (and reversing), and there are many valve gear designs to choose from.