OK, so we fired up the 455 for the first time today. I prelubed it with an electric drill on the oil pump shaft, to make sure that the oil pressure was ok, and that it wouldn't run dry for the first seconds. Everything was covered in assembly lube, of course. After some minor problems with the ignition setting and fuel delivery, it started. Well, after about 30 seconds at 1800-2000 RPM, it started misfiring on one cylinder, and we immediately shut it down. We removed the passenger side valve cover, and noticed that some of the rockers were loose. It turned out, that one pushrod had snapped almost in two, and the remaining 15 were bent. The rockers are 1.5, and I found no evidence of pushrod hole interference. I milled the heads .030 to raise compression, but still used the stock pushrods. I guess the stock valve spring shields bottomed out, or the spring retainer hit the valve stem oil seals because of the increased lift, the lunati 60902 cam delivers. I'm gonna start pulling the heads tomorrow to find out. Talk about a setback!
I'll let you know, as soon as I have identified the problem.
/Jesper