Single row roller bearing. Fitted to all pushrod and sidevalve engines (from 1930's to late 1950's).. These are original high quality RHP bearings (plastic sealed), in the correct C3 fit.
Update Feb 2021 - Sorry, but now out of stock - and obsolete/unavailable from the original high quality RHP manufacturer. The price has been updated to reflect a quote I have had to source this bearing from one of the specialist suppliers still holding a handful of them - email us on firstname.lastname@example.org if you wish to order one and we can confirm cost/availability, and may require a deposit.
However, as at early May 2021 - we have obtained a small batch of remaining RHP brand roller bearings for this model, but in non-C3 fit version, see Item listing 1009 in this same section. We can also obtain the correct C3 fit from a lesser quality brand - NKE, email us email@example.com if you would like more information on these.
Final point on ball and roller main bearings fitted to 1930's/50's OHV and SV engines: Unusually, Norton's showed a roller bearing being fitted on both sides of the crankcases on OHV/SV engines (i.e. 1948 catalog), with a ball bearing fitted just on the outer drive side. However, I have stripped OHV engines down in the past where a ball bearing is fitted both sides, with just the drive side inner being a roller bearing (as was the case with all SOHC engines). Not sure if it makes a great deal of difference - as like the SOHC engine, the OHV/SV engine was locked to the timing side bearing - but worth noting if you are struggling to find two roller bearings (and once ours have inevitably ran out)