Al, what is suspected is that in the front of the block at the oil pump is an auxiliary fitting to run an oil line from there to a pickup in the side of the oil pan if you wish. I used an internal pickup. What we found is that when the bore was machined for that aux port to connect with the intake side of the oil pump it broke into the distributor drive gear bore which caused air to get into the system. This was found after it heated rods number 3,4,5 & 6 but the mains were fine. It's still a lot of theory other then we do know of the intersecting bores. We're waiting on World's inspection report. I don't want to sound like I'm bashing World in any way.