I too agree,it maybe less messy to adjust rockers. Also would aid fresh start-ups, oiling valve springs and pre oiling pushrod, valve and rocker tips. May offer visual on oil drainback and oil spray characteristics. Andy could probably rate the last part based on his experience of the visibility quality available. Aluminum tops could be substituted for continued use if the were less expensive and more durable. The clear top could be available as an optional piece for inspection purposes. The real problem is the same as aftermarket blocks presents. Less BBM engines being built. Production costs/sales may be cost prohibitve for manufacturing. Now if you're a builder of multiple BBM engines and combinations of this engine, there is no denying the value of this helpful tool. As a side note, it sort of helps make the case for hydralic roller cams for anything but all-out combos. Extremely nice product and workmanship on Andy's covers! Bill