Hal,
It sounds like your builder new his stuff. If the engine is built correctly and oiling system is good, cam choice made for the combination, carb right size for engine and a few other variables an engines should run for 100,000 or more with little up keep other than
oil changes and cooling system flushes. The biggest problem we see is over carburetion causing fuel to leak down past the rings and diluting the
oil. The break down in the lube system causes wear on the moving parts, hardening of seals and sooner or latter frozen
oil control rings followed by smoke and worn bearings. If an engine well built it will take the hard running of a track every now and then and still be a good driver showing no ill effects.
Of course a well set up fuel injection system will go even longer due to it's ability to more precisely control fuel flow but htat is a whole other thread!
What do you think about synthetics? Just want to know if your thoughts are the same as mine.
Thanks for your service in the service. Because of folks like you, my father and my son we get to enjoy this country and our cars. We owe all of you our thanks.