TVR’s first engines were V8s (in the Cerbera), these were pretty good (4.5 better than 4.2) but need more fettling than the relatively low stressed Rover V8s that came before. They then introduced the Speed 6 (straight 6) and as Tiger6791 says this had problems with the finger followers – there are various mods out there that claim to solve the problem. Suggest you ask on Pistonheads or go along to your local TVR car club meeting (non-members will be welcomed) to get a ride in a few and talk to owners.