Camshaft bearings.

[englishmaninwales]

I've seen some horrible machining mismatches in the Rover K Series engine, especially between block and bearing shells. However the worst example was the oil feeds to all 8 exhaust hydraulic cam followers, the feed missing the oil groove in the followers by about 95%. A bit of energetic driving plus aerated oil made an awful cam follower rattle.
But then Rover went bust.....

[types26/36]

I've seen the misaligned oil hole on a few TC engines but it has always been on the exhaust side and I have only seen it on BV heads (that's not to say it is not on other heads) but it has never caused a problem that I know about.
I wondered if Lotus did it deliberately to try and reduce the oil being fed to the exhaust side as the drainage is not good particularly around #3 & 4 exhaust valves.
Of course it could just be bad design/machining but Lotus had been producing the heads for a while and I would have thought quality control would have got better not worse