[madmaxx]

You dont know it is set at zero, it may be set anwhere from 1/4 to 3/8 turn and it will do what you are describing. The advantage to setting the lash close to zero is if you float the valves (lifter pump up) they will not hit the piston. The disadvatage is if the valve train wears you will get lash and noise. The probability of you wearing out a vavle train in a cobra is .0000001%.

If they are set as zero as you feel they are you probably get some noise. Factory cars are set with .015" preload.

If you have high rev lifters which restrict the travel of the lifter plunger I think? you set 1/4 turn if you do more you might bottom out the plunger and now you have solid lifter which in some cases could hold a valve open.