Originally Posted by Multi-Engine Guy

Well, I will agree with that. As far as the early Sf abc series, pretty sure the early ones were chrome.
But whatever the alloy was that was used, it worked well.
In fact perhaps too well. As I had stated earlier, most of my O.S. 46sf ABC's have been flying for decades.
And are still running Strong with no noticeable loss of compression. Believe it or not, struth.
All I have ever changed out during an overhaul on these engines has been the worn out bearings, o-rings and gaskets.
I also use these non piped as well , lately with Bison mufflers. And they work great.
So, could it be that O.S. decided that maybe making bullet proof engines that can last forever, wasn't actually in their best interest and changed the makeup of the alloy?
Or perhaps the original alloy combination was too expensive and switched to nickel?
I'll bet some of my engines are as old or older than some of you.