Flat tappet lifters

[SSDiv6]

Originally Posted by SuperStock172

Thank you for the response, starting to get a lot more confident with this type of setup. Given your Boss' past experiences within NASCAR would you be able to comment on a camshaft specific question? My question relates to cup style camshafts being apparently designed to loft the lifter and hence giving the valve additional "dynamic" lift whilst running. Is this something that you or he has encountered and if so how would a DLC coated lifter hold up in this scenario? As Alan mentioned above you don't want a DLC lifter bouncing around so to speak because it will have the same result as a Schubeck, thus it seems strange to want to design a camshaft to loft the lifter with this potential catastrophic result. Any input would be highly appreciated.

NASCAR cams have never been designed to have an inherent loft or separation at the nose of the camshaft lobe. This type of event would damage or destroy the valvetrain and engine, especially during a 500 mile race. Just imagine the end result of the engine due to lofting taking place at a constant 8700 to 9400+ RPM's during a race.

The main root cause for a lifter to loft or jump the camshaft nose is inadequate open valve spring pressure. Dwell nose camshaft lobe designs have less propensity to loft.

Nevertheless, in a nutshell, the key is proper selection of valve springs to prevent lifter lofting.