Jordan,
Construction hints/suggestions for Romulus were "serialized" in the 7 1/4" Gauge News back in the late 1970s, possibly the early 1980s. Geoff Oughton, who worked with Roger Marsh to build the first two versions – a Romulus (0-4-0) and a Remus (0-6-0) wrote up how to do the major machined items. The series was in issues 4 to 7 inc. but there were other articles in various issues by people who had built examples and had them running.
The design was intended for "bush engineering" with the minimum of components needing any real precision, eg., cylinders, valve gear, wheels so that, theoretically, the rest could be done with files, angle grinders and Black & Decker drills.
The interesting thing about Romulus is the number of variations made – side tanks, well tanks, no tanks but the water in a tender, George Smith even extended the frames to make his an 0-4-4 sit-in type. Roger and Geoff intended that as long as the critical design parameters – boiler design, wheel diameter, valve gear and cylinders – were maintained, whatever else the builder did cosmetically wouldn't adversely affect the performance.
They are good steamers and powerful locos. I've got 4 superheater flues in my boiler and Roger's original sales blurb did say that superheating would improve performance. Most are built saturated though.
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All the best
Jack Meatcher (7 1/4"G Society member 191)