At revision work should not be left to chance, each component should be properly scrutinized before being taken back placed. When the valve spring seats is not that much different, check for cracks and if they are not bent. If in doubt, you should replace them, prevention is better than cure and especially in cylinder heads, a loose valve can be damaging. For any kind of overhaul and tuning we have the correct valve spring retainer, check them one by one and make the right choice. Only 8 pieces supplied.