I have 5,000 miles on this rebuilt motor. 1956 235 car motor. I noticed the other day there was more clicking in the valves than normal. With the hyd lifters they are pretty quiet. Pulled the v/c and found the intake on #2 had clearance at the stem. The adjuster screw had beaten down into the pushrod cup. Both are ruined. I have a spare pushrod and found the screw here in parts wanted. This was the only adjustment screw that was suspect looking. Plenty of oil on valve train. I don't know if the new hyd lifter is failing or not enough oil is being put in this area from the lifter. Maybe metal fatigue? I repeat this is the only one with a problem. Any ideas? Thanks Sharon