[CRZN427]

From what I remember on my research, several years ago, the machining of the block is only part of the difference between the final products.

The biggest difference is that the SO blocks were cast with a different, stronger, alloy.

The next thing is that the cranks were cross drilled on the main bearing journals, the standard FE crank has only one drilling, and the rods journals are drilled, the standard FE rod journals are not drilled. Then there was something about the radius on the bearing journals, something to do with relieving stresses.

The last item was that the main bearing caps, the ones in the center of the block, were cross bolted. That involves a different web casting in the block as well as different caps.

The changes were made to give the big block much more duarbility in the high stresses of racing and the changed made a very significant difference in the performance of the engines.

If I miss remember, please correct my thoughts.