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Read about 440 blocks, thin walls?

I still don't go by any of that info. I sonic check all of my blocks. I have seen so called thick wall blocks that can't even go +.030 over.
 
I still don't go by any of that info. I sonic check all of my blocks. I have seen so called thick wall blocks that can't even go +.030 over.
This X 2. Same goes for the cold weather 400 block nonsense. I’ve sonic checks those with results from excellent (.200+) to totally useless and tons of core shift.
 
What they don't talk about is the "hardness" of the later blocks.
I don't know what you guys have experienced, but I've noticed when drilling/grinding/etc on the later 70s blocks it's noticeably easier than the earlier ones, leading me to the conclusion that the later castings may be fine on thickness but softer in composition.
 
What they don't talk about is the "hardness" of the later blocks.
I don't know what you guys have experienced, but I've noticed when drilling/grinding/etc on the later 70s blocks it's noticeably easier than the earlier ones, leading me to the conclusion that the later castings may be fine on thickness but softer in composition.
I have noticed variations in hardness but nothing that followed a specific year or casting number pattern and the factory blocks were all noticeably softer than the aftermarket blocks. My hone was an HP6A Diamond hone so it didn’t really care how hard the blocks were. The ductile iron sleeves I frequently used took a touch longer. I’d hate to hone those with a vitrified stone on a sunnen machine.
 
I do know one thing. When we machined and diamond honed my Mega Block the guys mentioned it was the best quality high iron block they have ever machined. Even better than all of our Dart Racing blocks.
 
The Mega blocks were all nice blocks. Wished I would’ve bought a half dozen more back in the day.
 
I know when I picked up a 413 block after it had been bored, the shop owner was cranky. He hated boring Chrys blocks because he claimed the metal was so hard......
 
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