Fitting new main bearings on the crank

16 thou is fine. Need to see a pic of the cut-outs, never seen these before, normally one side has the part number etc and other side is smooth. Its good practise to be able to read the part number with the bearing in the housing but it achieves nothing performance wise.

They are just the way the cage has been machined and there is one for every roller so something to do with spacing of rollers. Not seen it before but cannot see why in or out would make any difference as it spins at 1/2 crank speed.

Your measured endfloat of 0.016" is right in the middle of the range listed in the factory manual so you don't need to do anything.

See attached.

Another good tip is to measure the end float prior to splitting the cases. It then gives that you know and then work from to easily correct if need be. 

or if replacing mains, keep old ones and enlarge bores of inners and reduce outer diameter of outers so that they are push fit on crank/cases, to ease endfloat checking in trial assembly.

The cage rotates at half engine speed but I do not see the relevance.

Not something I knew Tony,  not something I would even have thought about.

The superb photo from Mark Tomblin and use of magnification does reveal some yarn fragments. Look in hole with circlip for clearest example. Mark did his best with a clean cloth. Look at the dust sticking to the oil on the cage. Machined alloy around the bearing shows porosity in casting. Always present and this very acceptable.

I've worked in clean rooms with only blue Kimwipe tissue, spotless tools and plastic covers over part assembled engines. Grease in tubes so no grit in there either. White smocks too.

Don't set the bar too high Ian.

Mark looks to be doing a great job. I'm remembering some of my kerbside repairs in the wind and rain.

Peter

IPeter,  It probably stems from my time building F1 engines for March Racing and Sir Frank Williams. Old habits and all that.

As you say a good picture and good points made. I also remember the odd kerbside repair in the rain. But of course in those 'halcyon' days we knew no better or at least could afford no better.    With today's understanding we realise that cleanliness is next to godliness. Take it home in the back of a van then sort it in the warm and dry.