[QUOTE=LMSRACER;5335556]
As for the Main Webbing Issues, that is more of a 400 Block Issue than a 455 Block Issue. In almost every case, the 455's Main Webbing is much thicker than the 400. Look for a 1970 to 1974 455 Block.
[QUOTE]
Can you explain how you come to this fact based on two major differences in amount of material in the block casting, a 455 has larger mains and a larger bore. In most cases the 455 blocks where drilled if not drilled and tapped for the outer 4 bolt main bolt holes, again a decrease in material and strength.
What main webbing on a 455 is specifically thicker than a 1967-to 1969 400 block.
I would like to learn what block castings you are specifically referring to and what specific area of the block are you referring to as being thicker. Would you please post a picture or a casting number that you are referring to.
