Originally Posted by oldbogie
It never really ends anymore because the chemistry of oil has changed greatly and the old levels of ZDDP just aren't there to protect the flat tappet style cam and lifters. This is one reason (and a big one) the OEMs started to replace the flat tappet cam with rollers back in 1985. Others are reduced oil pressure and viscosity, elimination of indexed streams from the rods to pressure lube the cylinder walls and the cam, less drain-back and throw-off from lower pressures and tighter clearances, the use of a windage tray which cuts the mist flying around with the crank assembly. This combines in a hot rod engine with a more aggressive modern cam profile which is to cut back on long ramps that ease the tappet into motion and the use of higher lifts, cams like the Thumper, Extreme Energy, Voodoo, etc. get right too it with short fast acting ramps. This adds a lot of power and makes better use of compression ratios with unleaded fuels and high overall gearing but it's hell on the valve train parts.
Certainly nitriding or Parkerizing the cam will put a permanent hard wearing surface on it but to be safe it would continue to be a good idea to use a ZDDP booster. ZDDP forms a sacrificial coating on the cam and lifters similar to the chemical/heat hard overlay surfaces which by the way GM used for many years before ZDDP became popular in oils. But the ZDDP has to be constantly renewed as it gets used up between oil changes. GM had a lot of flat tappet cam and lifter wear problems when they stopped Parkerizing the cams and lifters of production vehicles back in the 1970's.
I have never been enamored with Chevy's idea of using the angle of the lobe and convex surface of the lifter that is there to cause the lifter to spin on its axis as also a method to preload a thrust force on the cam to stop it from longitudinally travelling in its bearing bores. I have forever build the Chevy with a roller cam thrust button to pick up that load as I figure the lobes and lifters have plenty enough to do without keeping the thrust load against the cam's movements.
There are many shops,ours included,that refuse to build anything but a roller engine,hydro or solid.
We too have seen cam failures many miles after break-in.With oil change intervals being at 2500 miles and the added costs of a Joe Gibbs racing oil adding to that oil change each one,your ending up paying for the roller conversion alittle at a time.It doesn't seem like alot,but it adds up.All that aside from putting the engine at risk for major damages.
It is true now that you have metal in the oil passages,it needs to be torn down,hot tanked,and the tolerances checked in a do-over.And do-overs almost always cost more than the roller conversion would have in the first place.