The problem isn't the timing chains as such but the tensioners and guides. The early versions had tensioners with steel pins pushing on aluminium backed guides. The aluminium wore down and the guide couldn't hold the tension.
My previous D4 V8 had these guides but was still nice and quiet when I sold it with over 200K km and it was sold again with over 250K. This engine had regular oil changes at half the interval recommended.
My current SCV8 had the timing chains and guides replaced when it developed a noisy top end due to a worn exhaust valve tip and bucket. It had the steel guides and everything was fine. This was an expensive repair as I changed all the exhaust valves, timing chains and guides, coolant hoses, water pump, supercharger bearings, supercharger coupling, supercharger oil, 5 injectors and all the associated gaskets.
I'm not sure why the valve tip wore but the car had been serviced to at the recommended intervals before I bought it.
Greame Cooper Automotive did the work for me and did an awesome job sourcing parts, dismantling and putting it back together. They had done a timing chains on a few NA V8s before but not a SCV8. The car has been faultless since then.
I haven't been able to find any others with worn valves so I may have been unlucky.
I have heard of big ends failing and a LR workshop manager I know who worked for a dealership in Sydney attributed them to a certain demographic who overreved the engines and/or held them at sustained high rpms.
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