The Zetec is very much like a solid lifter motor. The cams push on a bucket which directly moves the valve. Its a little noisy because of this. When I installed my crower cams, I had to change the thinknesses of a few of the buckets. Some of them were on the loose side when I checked clearences. It was even more loud because of it. There is no adjustment that can be made except actually switching the "lifters" or in this case buckets.