Cam bearings were never fitted to the Triumph GT6, TR250 and TR6 engines during production.  All GT6 and TR6 blocks should be machined to accept camshaft bearings, whether using a stock camshaft or any performance camshaft.  Every GT6/TR6 engine we machine and build in-house now is modified to accept cam bearings, regardless of whether it is a stock engine or a full race engine --  all get camshaft bearings installed!
Additional durability and performance can be obtained by selecting our performance coating option.  The coating is a very thin sprayed application of a moly based material which has exceptional film strength and reduced surface friction.  The structure of the dried moly film is semi-porous and will hold oil on its surface.  The coating film reduces wear in low oil situations, such as engine start-up or in the event of a lubrication system failure on a race engine.
Machine engine block cam tunnel to 1.969" +/- 0.0005" to fit cam bearing set.