<< When my dad pulled the head off he told me to have the valves ground (says the engine will last longer) >>
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Actually, depending on the engine's milage, doing just that may shorten the engine's remaining life. The valves seal the upper part of the engine and the rings the lower, creating a "vessel", called the combustion chamber, that is fairly air-tight.
Both the rings and valves wear together......both losing its seal equally, at least that's the hope. Typically, as both the rings and valve seats wear out, the compression drops.
Now, take an engine with wearing rings and valve seats..........regrind the valve seats so the seal is like brand new. Now the compression rises, but the rings haven't been replaced. So now, the worn rings have to seal against that increased compression, a compression they haven't seen since they were new. This increase of compression can cause a quicker failure of the rings.
I've seen numerous valve jobs done with replacing head gaskets.......mechanics love doing this for you because they know sooner than later you'll start having lots of oil blowby by the rings and increased oil burning.