I'm running a 235' with a 848 head and a Mellings hydraulic cam. I'm not sure what head the 261 guys are running, with still a little knock in the upper valve train area I have backed off some of the rockers to notice some pretty deep prints on the rocker arm from the valve stem. I did not know if taking these rockers off and polishing back to a clean surface would be suffecient? This engine really runs good, but that slight little knock say at 1700 rpm's is not what I like to here.I have set the lifters the way Hot rod Lincoln explained to me. A friend of mine said to check the rocker shaft versis the rocker arms for clearance. You know by looking at some of the rocker arm numbers don't even match the shop manual numbers? The manual also mentions R/H exhaust/intake and L/H exhaust/intake now what determines this? Thanks there Bolters....