Nitrided vs Chilled 850 cam

On the topic of lifters, have the new AN lifters shown good wear or should i say lack of wear? And does the type of cam material need to be a certain one to match those lifters? Thanks in advance, Chuck.

SteveA said:

Always easier to buy stuff on the continent you live on! Include shipping an taxes and it's probably nearly evens.

Having a lifter solution makes the deal. But you do need to reface them radiused.

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Agreed. As for the radius I have a lathe with a tool post mounted grinder. Not the latest or greatest way, but it should work with proper setup.

Hundreds sold and only one problem from some one who really should have known better reamed the undersized tappet tunnels with no clearance.
As for the steel cams, not had one problem with those.
As for nitriding, why would anyone not plasma nitride a cam these days. Other older dirty and toxic methods maybe still used but you'd most probably need to ask for them to be used.
The tappets that were under test when the test rig failed and an old pair of 70's tappets gave a massive insight to what was happening on the interface. Had the rig not failed we would have never spotted it.
Sometimes going harder is not always the correct way, it can introduce more issues that can prove problematic.
Those engine builders here knew what worked, we looked at all the various combinations where it did using all the cams and tappets both two piece and welded face, when I put it together and the knowledge of those metallurgists from North America and Europe that make the one piece tappets and stellite weld rods, it all became very clear. We even cut and inspected a steel cam that we knew were in circulation, the nitrided case was none existant and still had white layer on it, again another useful insight.
Testing failed items is one side of the story, testing what worked is where the answers come from, but then no one goes to the expense of testing use but serviceable items.

Madnorton said:

snipped
Sometimes going harder is not always the correct way, it can introduce more issues that can prove problematic.
Those engine builders here knew what worked, we looked at all the various combinations where it did using all the cams and tappets both two piece and welded face, when I put it together and the knowledge of those metallurgists from North America and Europe that make the one piece tappets and stellite weld rods, it all became very clear. We even cut and inspected a steel cam that we knew were in circulation, the nitrided case was none existent and still had white layer on it, again another useful insight.
Testing failed items is one side of the story, testing what worked is where the answers come from, but then no one goes to the expense of testing use but serviceable items.

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Both Lycoming [late 1990s] and Superior Air Parts [FAA approved manufacturer of clone Lycoming & Continental Aircraft parts] have had issues with their crankshafts being recalled. These failures were also due to shoddy Nitriding of the crankshaft surfaces. See link below. Don't need to read the entire thing, just scroll down the section labeled Background. Note they also mention "white layer".

Airworthiness Directives; Superior Air Parts, Inc. Engines and Lycoming Engines Reciprocating Engines With a Certain SAP Crankshaft Assembly

Material isn't the only problem. The shape and geometry are just as important. See the flat lifter cam on left and radiused lifter cam on right (same lift and duration). Which cam do you think will last the longest?