You can set your valves a bit on the loose side if you have mechanical lifters. This leaves them on the seats longer and improves cooling. If you have a 261 it has stellite valves and better water passages so the seats last a bit longer. Most of the time the block and valve guides will wear out first. Don't worry until it is a problem. There is no point in doing a valve job until you actually need one, since they have to put insert seats in it anyway. It won't leave you stranded.

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A lone amateur built the Ark. A large group of professionals built the Titanic.