Hello Pat >From what you say, I'm sure that cooling is part of your problem. I don't think that it is the only one. Answer the following questions. What grade of oil are you using? Did you ever verify that the crank, rod and cam bearings were the correct size and that the gap when bolted were not too large? Another possibility is that the oil pressure relief spring is weak and when it gets warm it looses some of it's tension and lets the oil pressure down.
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