?? For Tom Renzo (the GM guru)
Reply #10 –
OK here is what happens when things are not assembled correctly. With this said it most likely is not a mixed up Push rod. Normally when you do that it is an instantaneous issue if mixed up. But depending on dynamic stacking it may have a mixed up push rod. But with no compression in the cylinder a leak down test is necessary to determine the valve that is most likely BENT. Or a tight guide is my thinking. I think the guide was to tight and the valve seized in it. And the valve hit the piston I have seen this many times in the past. A swapped push rod would have been almost immediate. Guide clearance is critical on these engines and they do have seazing issues if not assembled with the right clearance. The plug does not look like mechanically damaged. But without seeing it in person it is a tuf call. Pull the valve cover and eyeball the retainers after removing the rockers. You will see one that is lower than the others if the giuide and the stem seized.
Typical mixed up rod