I did open my already restored sidevalve to compare the castings and cams, yes, TT 2 is pukka racing parts, different castings with reinforced bearing locations, with cams with about 100 degrees of overlap and 9mm lift, not shabby for 1931 engineering!!!
Patrick
Hi Patrick,
You know, one of the falsehoods that is unwittingly perpetuated on the internet, and other places, is the idea that engine engineers of early 20th century (post WWI through the late 1950's) didn't know what they were doing. This idea however, is far from the reality. When you read the papers and books from these pioneers, it becomes obvious that they were hard working and very astute engineers and scientists, who advanced their projects using the scientific method. And in many instances, it was these pioneers who invented the methods and technology that we use and take for granted today. It is on the shoulders of these giants, and the ones who followed, that we now stand.
To be sure, these pioneers were handicapped by the metallurgy of their times, the infancy of production hot forging, the tediousness of hand calculation(s), and the lack of standardization, as well as other issues. But then, as now, there is little that restrains persistence coupled with ambition. And it is important to also note, that Postwar racing definitely benefited from the technological advancements of WWII.
Knowing what I know about the material specifications of the times, I'd say 100 degrees of overlap and 9mm lift would have been pretty cutting edge and quite racy for the 1930's. Quite probably near to the limits of their valve springs . . . . . .
I'm sure you already are aware of this, but it is always worth repeating. Re-manufacturing of the critical parts of these assemblies using "modern" materials, bearings, etc, can add life and reliability to these restoration projects. Especially where no reliability may have existed before . . . . . .
Mark
