All the issues start after the factory cam bearings get replaced.

That’s because all the production engines had their cam bearings machined on the ID AFTER installation.
Same thing for automatic transmission bushings.

They could hold tighter concentricity with this method.

This process is still in place to my knowledge.

I can understand how there can be a sizing/alignment issue in an OE block after the bearings get replaced........ because of the procedure being used by the factory for the finish sizing.

But there’s really no excuse for a $5000+ aftermarket block having the issue.
The cam bores should be in alignment and to size........ and so long as the cam is straight and sized within spec....... the cam “should” slip right in.
I’ve used 3 of the previous generation BM/Mopar aluminum blocks and those had no problems with the cam fit.

I pulled the cam, put in another cam, and it glides freely. So i checked the diameters of the new cam. They were all spot on with the other cam. So i tried reinstalling the cam that was tight. I cleaned the journals, put 20w50 oil on it, and it turns freely! I am scratching my head, and have to figure it was the type of assembly lube I used when I originally put the cam in? I used Lucas assembly lube, and it was tight on install, but after sitting for months, it got thicker? I couldn't turn cam with my bare hand, but after going to 20w50 it is snug, but I can turn it with fingertips.

I gave up using the old Torco brand red assembly lube after they got bought out back a long time ago.
The motor runs on oil, correct? So why not use that to assembled them on all the bearings, pistons and piston wall surfaces
I do
I prime all my motors and spin them over by hand or on the starter with all the spark plugs out before starting them to make sure they are well lube with the engine oil they will live on: up: