I would like to reenforce what Jim said. Check the alignment of the hole in the block and the main bearing. They do not line up well. #1 rod and #6 rod are well oiled, if the holes in the block and main are aligned. Also check the groove depth in the bearing. If you used the old bearings they could have been worn considerable. The rear main bearing especially. The research I did before building said to make sure the holes were in alignment and also to cut the groove in the new main bearings wider and deeper.
Hope this helps.
