[GTOLou]

Originally Posted by zeebo

so this begs the question..are there any differences in 455 blocks from 70 to 76? discounting the ram air blocks and four bolt mains in some....

I don't really think so. Certainly a 76 455 doesn't have the same weakness issue as that 76 557 block. Maybe older castings had more nickle?? - not sure that applies to the 455 blocks.

The 76 455 blocks were not drilled for four-bolt mains. Some folks think that may make them stronger as less of the meat has been removed around the crank for the four bolt caps. A studded two-bolt cap is plenty strong - especially if the block has not been drilled for four bolt caps.

If you "do" want to strengthen one of those 455 blocks, then you should only use splayed four bolt caps as a non-splayed four bolt cap motor may actually be weaker than a studded two bolt main motor for the reason above.