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Ha, he also states that all big block mopar blocks cast after 73 are THIN WALL and should not be bored more than .030 ... ...



He's pretty much on the mark about those 74-up
motors. Walls are not as thick as the earlier models, particularly the 70' and earlier.





Sorry , that is incorrect, AndyF. did an article a number of years ago that dispelled that MYTH , the later blocks are usually thicker. [/quote

Either Mopar Muscle or Mopar Action did a comparison as well. They tested 383s, 400s and 440s from the mid 60s to 1978. They found that the heaviest block was from a 77 440. It weighed 234 lbs. They sonic checked each block and also found variances that were surprising. Some later blocks were thin in some areas while others of the same vintage were really thick. One thing that was evident was that the later blocks were made of a slightly softer material. Larry Shephard may have been merely "echoing" the memos from the engineering department without any personal knowledge of the cylinder blocks he spoke of. The magazine that did the testing stated that the reasoning behind the "Thin wall" moniker may have had more to do with the actual material hardness rather than the thickness of it. They also went on to give this sage advice: always sonic test before going beyond .030 in any block.