Originally Posted By: Gary Allan
These are typically engines with higher spring rates. If you've got normal spring rates ...you don't have to worry about it.
No, if I think I know what you are referring to. Flat tappet cams/lifters need ZDDP to provide a buffer between direct metal to metal contact irregardless of spring rate. Flat tappet cams/lifters basic operating principle is direct contact, so you can see why a pressure additive is so critical to the life of these parts. This has been a very hot topic in the hot rod community and EVERY major cam manufacturer (Crane, Comp, Erson, Isky, Lunati, etc) say to use a oil with elevated levels of ZDDP in it if you are going to run a flat tappet cam. Call them and they'll tell you personally. In a perfect world every engine would use a roller cam, but that's not the case and hence the ZDDP issue.