Hey guys I have a 1967 440 with 915 heads full comp valve train and cam there 1.6 roller rockers with hydraulic flat tappet lifters and I lost some compression in a couple cylinders. So I did a leak down test and heard air coming from the valve train area so I thought maybe my rockers where out of adjustment. So I tried to adjust them I went to zero lash and half turn of preload and now there noisy clattering and they where quiet before. Do you think I put to much preload on or not enough?? Any help would be much appreciated thanks.