Twin row caged ball bearing. Fitted to Model 30M/40M (Manx) SOHC engines in original C3 looser fit, from high quality SKF manufacturer.
This is the twin row bearing fitted to the timing side of SOHC magnesium crankcase M30/M40 (i.e. pre-Featherbed) Manx models. It is different to the aluminium crankcase International models timing side bearing (which is only a single row bearing) - making the M30/Manx models stronger in this important area (which may explain why pre-featherbed M30/Manx magnesium crankcases are often found with the drive side crankcase damaged but timing side ok).
Original bearings had steel/bronze cages, but have not been available in that form for many years. Modern versions of this bearing are now supplied with a nylon cage. This is the correct looser fit 'C3' bearing as fitted to original models - but bear in mind the cage is nylon when soldering the whitworth screws over the bearing retaining plate - particularly if using a blowtorch, do not get the heat too close to the cage!
SKF is a high quality manufacturer of the same qualithy as RHP manufacturer, and now very difficult to find.
Update April 2020: For the last 5 years this bearing has been getting progressively more difficult to source, and back in 2019 we ran out of them completely. I have marked this listing as new again - to highlight to customers that we have managed to source a small quantity of this bearing from high quality SKF manufacturer in the correct 'C3' looser fit size (as originally fitted). although not cheap - if you have a magnesium crankcase M30/Manx, these are the correct bearing and not sure if they will be available again when these have gone