Not all flat-tappet cams are a problem but we have had more trouble with them in the last few years than ever before. The camshaft manufactores are saying that it is because the
zinc and other important additives have been removed from the
oil. We have been using Rotela-T for break-in along with GM OES additive. There are some special break-in oils out there from a few company's like Joe Gibbs for the flat-tappet cams. As long as the lifter spins and get plenty of
oil during break in you are usualy ok. We also use low spring pressure when we are breaking the camshaft in. It is just a lot of trouble for use and a possible problem when we are doing as many engines as we are the hydraulic roller makes more sense.
The proplem with the solid roller is that it normally requires decent spring pressure and the lifters have roller bearings in them that need
oil. When the engine is running at higher rpms it gets a lot of oil on the roller bearings. On the street the idling around is hard on these needle bearings in the lifters. They have come out with some street solid roller camshaft that do not have to have as much pressure and along with the new pressure feed lifters they are getting more life out of the solid roller stuff on the street. Just depneds on the power level and rpms that one wants. Good luck, Keith