In the L72 and L78 engines the valve springs couldn't keep the valve in contact with the valve train at much over 6K rpm. The valve would actually be free falling shut. Eventually the keepers would pound themselves through the retainer and you got a dropped valve and usually a broken block. That's how most L78s died. I must have had horse shoes as our L72 engine saw 6500 countless times. My racing buddy just shakes his head and cringes when I tell him the stories.
I never heard of any bottom ends letting go in street use.
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Chevelleless after 46 years......but we did find a low mileage, six speed, silver 2005 Corvette. It will just have to do for now.
