lifter clatter

In 2007 I got 2 of those bad batches of lifters in a row. Got tired of messing with them and switched to Lunati and haven't had a problem since. In your case it could be either defective lifters or like you think it may not be enough preload. The only way to know if it's a preload issue is to measure it. As for the pushrods being easy to spin meaning it's zero preload, that happens even when everything is correct cause all hyd. lifters bleed off a little when the engine isn't running. The only way to know if the preload is correct is to measure it.