I bet it is looser valves set up that way to break in the seat on very small light weight valves and springs. once the seats are broke in, the valves will need adjusting and will run quieter at the breakin tune up. When a valve seat is cut, itis cut at certain angles and depths leaving a narrow land, which is the seat. It is not finished it will get pounded by the valve, minutely wider and fit to the valve. The seat will only pound out so far because it will workharden. with hydraulic lifters, you just break it in and keep going. With shim or screw adjust you need to check the valve clearance to make up for the added slack of the break in period. it is small clearance, but it is noisier, and it is detracting from the actual cam lift by the same amount that it is out of spec. so look out when they take that .0015 to .003 outta there, wheelie machines everywhere!!