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 March 2021 - we are looking at options, and are hoping that we may shortly have some RHP non-C3 (tighter tolerance) version of this bearing - circa £120 each, or the correct C3 type from an alternative supplier, which should be much cheaper. Again, email us on email address above if you want more information or to reserve one of these bearings for when they come in
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)