Personally from what I have seen these days even [retrofit] roller cams aren't safe from failure.
Anyways, I have done 4 cam installs, 2 350s, slant six, and a ford tractor, all flat tappet, the 350s being hydraulic lifters and the others being solid lifters. Have not had any issues/failures from any of them. The 79 has a Summit cam and lifter kit in it, the 76 a Howards cam kit, and the slant six has a custom ground cam and lifters from Oregon Cam Grinders (in Vancouver, WA).
For all of these installs I used lucas assembly lube on the bearing surfaces and moly lube on the lifter faces and cam lobes. None of these engines have crazy profiles or crazy high spring pressures (so I am sure that helps overall). I think break in springs or removing inner springs is a good idea for higher profile cams/higher spring pressures/rocker ratios.
If your old lifters are in good shape, Oregon Cam Grinders can resurface the old lifters to recrown them and be able to run with your new cam. Might be worth a call and see.
Yeah, I hear ya and I appreciate you chiming in. The lifters had been pretty galled on the side (same as the the bearings) from junk that had circulated through the oil, likely on startup from the prior “rebuild”. All the flat tappet stuff I bought is already in the mail for refunds, and some of that is just to get it back before 30 days, or else I’m stuck with restocking fees if I can return it at all.
Part of this is saving me from myself. There’s so many variations and variables out there, how they fail, why they fail, what happens, etc, and like anything else the devil in the details. That is something that I can’t reconcile from my garage, I was trying to do exactly that (calling and talking to people, watching YT, etc) and it was driving me crazy to the point that I even my wife was noticing.
It’s true that roller lifters fail too, but they typically fail in a different manner (lack of pump-up, etc) versus flat tappet either surviving or failing during break in- or even a thousand miles later. And with the lack of cores and dwindling supplies or cam cores/lifters, they might be hard to obtain in the future. Hard to say.
I will say that it will be nice to not have to worry about the cam so much when I fire it up for the first time.