The blocks have the oil hole from the camshaft to the mains right down the middle of the block. This is weak erea of the bloc
Excaliber,
I'm aware of the
oil hole on the top of the cam. The weak area Keith points out is the cam to the mains. Even SO's crack here. I just sold a CO to an engine builder b/c his customers SO cracked in number 4 main to cam. I also passed on a so that cracked in that very spot 10 years ago. I have heard quite a few guys on the FE forum with SO's that cracked in the same place. All the blocks share this weakness. The little hump in the top whether drilled or not does not change the strength