Just as you say; the rod isn't centered over the bearing; it's toward one side so that the cylinder above it can be moved to get more room for a larger bore. Obviously this isn't ideal but you are correct about it not being much of a compromise. I think the biggest down side was that it required assemblers to pay attention because 4 were off set one way and 4 the other direction. Reading about this again I think I said it backwards before… "The cylinder centers were judiciously moved, resulting in the narrow 3.5 in spacing being increased to 3.625in, the intermediate spacing being reduced to 3.8125in, and 0.125in being removed from the center spacing to make it 4.0.”
From:
http://www.sae.org/technical/books/R-365
