I found this TSB in my Collection of Ford Literature. I am sure everyone is aware that the Original Torque Specs caused the Blocks to Crack. Finally in Dec 1956 Ford realized there was a Problem and changed the Specs.

  

Thanks for sharing that.  That's pretty obscure in putting that main bolt torque spec correction on page 7.  It’s no wonder there were so many issues with over-tightening the mains on the 312 engines.  To date, I've only found the cracked main webbing on those blocks that were into after they left the factory.  Never found a cracked 312 block at the mains on those engines that had never seen bottom end service.

Lorena, Texas (South of Waco)

Those TSB's were only issued to Ford Dealers. I wonder how long it took for that to become general Knowledge outside the Dealerships? Possibly why You have only seen Cracked Blocks after they were serviced at other than Dealers.. Maybe trying to fix Rear Main Seal Leaks?.

  

I seem to remember  the  the rear main having shorter bolts then the other 4 and being told that using long bolts in the rear would result in cracked webs

The Motor's Manual that I have still has the old figure listed.  I think the one I got is a 57 or 58 issue.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ