Hello everyone. I swapped a 2005 hummer 6.0 lq4 into my 78 Chevrolet van. That was about a year and a half ago. Iíve been all over the country without any issues. The engine had a little over a hundred thousand miles and all I did was put some freshly machined stock 317 heads with new hardware on the motor. A new oil pickup tube with O ring and brace. Also changed the lifters and trays to genuine ls7 style. Motor is bone stock otherwise, excluding some long tube headers and an intake. Always ran great and dead reliable. Some pinging uphill on 87 on rare occasion but Iím generally quite easy on it. Yesterday she started clattering on the highway. Made it home but now itís got an audible miss and still clatters like hell. Sort of sounded like a bad lifter from the passenger side. Ended up pulling the head today and found nothing apparently wrong. All 8 lifters look good, no rollers had come apart. No bent pushrods or bad rockers as far as I can tell. Oil looked okÖ no major metal flake. Only thing wrong I found was a burnt electrode on the front most cylinders plug. Could be from the bouts of detonation I experiencedÖ unsure. Where should I look next? Could my cam have gone flat? I didnít hear anything in the bottom end but perhaps something is failing there? Please shoot me some ideas. I have tons of photos but donít know how to post them