Block Hardness Testing

[Katz427]

One gent I used as my reference on anything cast iron, was a metallurgist with time at the Ford Cleveland foundry. I asked him once about the "P" blocks and the very small amount of phosphorus added to the mix. Like "What they do that for"?  His answer was it made the "pour" more fluid and better mixed, this gave a more even distribution of the carbon, ( which increased strength) and the fluidity, helped the fill of the mold.

[babybolt]

Using the tried and true and very accurate tap the block with a hammer method, the early FE blocks are harder than the 70's trucks blocks which might have used the same iron specs as the 429/460 blocks that are supposed to be more ductile.