[chiphead]

I'm discounting the bent pushrod thing right now. I'd want to see pics of these pushrods before I call anything bent.

I also want to see pics taken while this engine is being disassembled. PIcs of valley pan installed, then removed, then pics of how pushrods fit in lifters, pics of the amount of preload, etc. Do not disassemble the rockers or pushrods, take the valley pan off first. This will show how good you guys really are at setting valves.

I'm leaning toward minor contact between lifters and valley pan. Unfortunately, the only way to 100% check clearance is to fit the valley pan on with the heads removed, which allows direct observation of the clearance. Witness marks may be present, depending on severity of contact and how long its been hitting.

Collapsed lifter is another possibility. A fully collapsed lifter is easy to see, the plunger is stuck partway down its travel with pushrod removed. A lifter that is not collapsed but won't function properly is harder to detect, as the failure to function is only apparent when it's running.

You might could pressurize the oil system and roll the engine a few revolutions by hand and see if you notice a lifter that is not flowing oil to the pushrod, or is not lifting the valve properly as the cam lobe picks the lifter up.

Since you can't disassemble the lifters, the only option is to replace the set. I know that Paul modifies the lifter bores of his builds to run the highlift-johnson slow bleed lifters. I'm using the same ones in my build, and they are very nice pieces.