I've installed those on 3 different engine builds. I noticed that the small hold downs for the rockershafts vary in width. They came in 2 sizes and varied by .005". I had fun with the first set shimming the rockers till I discovered this. On the last 2 sets I just marked the wider ones so they were installed to a specific stantion. The last set proved to have another problem. The rockershafts themselves were too large in diameter as to where the shims would barely fit over the rockershafts. Spent unwanted/wasted time making the shims and rockershafts fit. Would I use them again? No.