I didn't speak of their quality, just of their temperature range accuracy in the Fords. I'm not saying that you are wrong and I am right. I'm just sharing my experiences in that others may use it to find their own path.
When I actually relied on them, the main issue I had was that they had accelerated tip wear.
I do not have any experience with the original Autolite 's but do with the Motorcrafts and some with the AC's.
To me, the Motorcraft and the AC's are the same plug and I originally had issues all along compounded with weak stock ignition systems.
Then, all I could do was deal with it wrongly as a plug temperature range issue. Now I know better.
That just manifested itself when I started with Webers in about '78. That needed to be resolved and now is. Once the spark strength was there, the temperature ranges of the Motorcrafts became effective for me and the 32's worked and became the plug of choice.
If you run a stock ignition system, issues will/could emerge and look like the plugs.
It is important to acknowledge that there are multiple factors running concurrently here and it isn't just the plugs. For instance, if you change the cam from stock, that's another factor.
A BF42 is an adequate solution, albeit a factory band-aid but don't blame plugs for other issues/considerations. It actually is not simple and gets complicated including what spark plug wires you are using.
Remember the factory's concern over 7-8 cross fire?
