This is just a curiosity question/post. I've looked at cutaway images that show the difference between flat tappet and roller type cam/lifter setups. The flat tappet has high loading at peak lift, as the cam profile is very aggressive. The roller setup allows the cam profile to be more smooth, distributing the load much more evenly as the cam makes its revolution. This lends credence to why some suggest the use of HDEO and/or oils with good amounts of AW additives (ZDDP for example) for flat tappet applications.
What about OHC engines, especially where the valves act on "bucket" lifters? That setup (which I'm much more familiar with, and have seen on many engines) seems a lot like a flat tappet OHV engine, similar cam profile, or am I wrong? Is there an inherent difference in cam/lifter loading that I'm not seeing that would necessitate an HDEO (or other oil with improved anti-wear characteristics) in a flat-tappet OHV versus a OHC cam-over-bucket setup that traditionally uses normal PCMO?
When did major manufacturers transition away from flat-tappet OHV design? I know my 1985 460 has the setup, but not entirely sure how long this design persevered.
What about OHC engines, especially where the valves act on "bucket" lifters? That setup (which I'm much more familiar with, and have seen on many engines) seems a lot like a flat tappet OHV engine, similar cam profile, or am I wrong? Is there an inherent difference in cam/lifter loading that I'm not seeing that would necessitate an HDEO (or other oil with improved anti-wear characteristics) in a flat-tappet OHV versus a OHC cam-over-bucket setup that traditionally uses normal PCMO?
When did major manufacturers transition away from flat-tappet OHV design? I know my 1985 460 has the setup, but not entirely sure how long this design persevered.