mystery engine number

[colina]

Thanks - so maybe I have a Thetis (or at least one originally built as one and then converted?). Does anyone know if that engine was different from the car version (apart from, perhaps, the oil cooling?).
I'm not looking for total originality and it will only be a 'good weather' road car so I am not planning to do any significant performance modifications engine-wise

[Chris Garner]

I don't think there was any difference between a Thetis crankcase and a standard car one. Thetis engines were supplied in both magneto and coil formats. The Thetis engine was always a 3-bearing type.