[Healeys] Bearings

[sebring at illawarra.hotkey.net.au]

I am by no means an expert but multi layer shell bearings were developed to (a) provide a shell backing to allow ease of having spares on hand,  consistent sizing and ease of replacement. No machining of the bearing assembly.  (b) the backing layer is harder and has a higher load carring capacity, therefore made of different materials.  (c) the facing material is relatively softer so that small imputities that come with the lubrication oil can be embedded in the bearing material rather than scour the crankshaft journal. 

Generally it is better to replace worn bearings rather than grind cranks. Inspection of well lubricated but worn bearings will often show the different colours of the soft layer at the joint line and the load carrying  backing as a different colour underneath.