[quote]Any idea if a Lionel U30C Diesel Engine (6-18276) will work on O-27 curves? No switches are used in the layout. Thanks for your help![\quote]
No, minimum curve is 31 (it's listed in the catalog). Flanges will work on O-27 style track but you need O-31 diameter curves or larger. At 18" long the model is scale or very close. On an O-27 curve the overhang will be really, really, really bad and that's assuming the three axle trucks wont bind on a curve that tight.