Lewtot184, that would make sense to me and would explain the measurement I got. Doc, the 516's are looking better for this build. I know I'm leaving power on the table using them, but I have to stay within the budget and that means using what I have. Makes me wish I hadn't traded away the 915's I had, but I wasn't thinking of building a big block at the time. I picked up Summit's 6400 and 6401 a while ago and have them sitting on the shelf. I've thought about giving one or the other of them a try. If I don't like how they perform I can always swap in another cam down the road.