Don; I noticed the same problem when I switched a '65 413 into my '65 New Yorker. I had to go back and change the oil pan to one that would allow a full range of motion for the idler arm. Couldn't figure out why it didn't want to turn very sharp to the right 'til I looked underneath at the dimple that the idler arm was trying to make in the oil pan..... Of course, having to grind the block for the different engine mounts was a treat, too. I only found that out after I had assembled and painted the engine prior to installing it. Cheers, Roger