small block cam issues...rattley new engine!

I think Rumble is on it with the lifter preload. How much preload do the lifters have? I haven't ran a hyd. roller but I remember a few yrs. back one of the guys on here put a new Comp cam hyd roller in his sb and had noisy lifters and when he talked to Comp about it they told him to preload the lifters 2-1/2 to 3 turns. He did it and that quieted them down.