Let me tell you about my experience with flat tappet camshafts. I do a lot (average 10 a year) of ISMA 2 barrel engines, by rule, they are flat tappet camshafts. For the 10 years prior to the china flu, I never had a cam go flat. Now, if you get a cam lifter package, I would say you have about a 40% chance of not having a failure.
Here’s a small list of some of the things the engine builders/ owners tried to avoid a flat camshaft.
80 lb springs = failure
1.2 rocker arms = failure
Manual rotating engine to make sure lifters are turning freely, then run starter while watching them = failure
Preheating the oil = failure
Yes, we run them up to 2000-3000 within 10-15 seconds after starting.
Now, I am sure some of the internet experts that have not broke in multiple flat tappet cams in the last few years will tell me “you don’t know what you are doing”. LOL
What has seemed to work, is having their used lifters “rebuilt”. There is a place in Minnesota, which rebuilds them for under $4 each. I have done 3 engines with “rebuilt” lifters and new cores and no failures so far.
This whole situation makes me sick.

Joe