I saw on a few threads on other online hot rod forums where a few engine builders have started dissembling and inspecting the new flat tappet lifters before they were installing them. The report is that many have come in without the springs inside, or had the plunger in cocked so it couldn't move, or the fill port plugged up or sticky so it couldn't pump up with oil. Apparently, they have come across enough poorly assembled liters to warrant dissembling and inspection of each one before installing them.

I have no idea if that is factual or not, just passing info I've read on. In the grand scheme of things, it makes more sense having lifter assembly issues then it does having intermittent issues with oil break down on one cam lobe or an individual cam lobe hardness issue.

In this day and age, I think I would take the time to dissemble the lifters and have a look see at all the lifters I was putting against a new cam. I'd only have to see one poorly assembled lifter to make it always worth the time to check them. Its a pain, but given the number of cam/lifter failures going on these days, an once of prevention might be the difference between being happy and not being happy.