Thread: 4 year old rebuild in Corvette - now tapping or knocking...leaking oil

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Originally Posted by lrsmith62

I guess I'd be shocked that the cam is worn our since I have less than 2500-3500 miles on this engine.

Today's motor oils no longer have zinc and phosphorus additives, which were there to deal with high pressure, point load friction, specifically cam to lifter friction. They were omitted when OEM's found that catalytic converters were getting plugged with heavy metal deposits, rendering them useless, and since OEMs had switched to roller cams they had no concern with changing the oils we can buy. If the cam is not broken in 100% perfectly, i.e. immediate start without extended crank, 2000 rpm for twenty minutes with no idling, a wear pattern can start that stops lifter rotation, and wipes a lobe quickly, often less than 2000 miles. Running a racing oil, like Brad Penn's or Joe Gibbs can work, but it's still a gamble.

gotcha....I'm not running a pcv system, but do have the draft tube and the filler cap is vented around the bottom side of it.