My best guess is that an intake valve is hanging open and slapping the top of the piston lightly. Pull the intake manifold and look at the gunk buildup on the valve - if there is a lot, that could be it.
Did you have the valves and valve guides cleaned or looked at at the machine shop? Or just resurface and go? These heads also like to drop the valve seat out of the head when overheated. Probably not your problem, but could be.
I had a machine shop go through the heads, they cleaned the heads, inspected the valves, guides for sure. I know that they had to replace almost all the guides. I'm not sure if they looked at the lash adjusters or rockers though.
Did you clean the oil passages with a brush while you had it apart? Could be a blocked oil passage reducing oil pressure to the head - new lifter won't fix.
The machine shop cleaned the heads, I didn't do anything to the block except clean up the deck.
The noise is moving at 1/2 the engine speed - top end related noise.
Engine was knocking - but much faster than yours because the bottom end spins at 2x the top end on a 4 stroke engine.
We thought the knock was engine speed. (I spliced your quote together)
This link takes me to a web design page... but I think I saw this on another thread. Is this the engine for about 2200 that they say fixed some of the factory mistakes?
That's what I just finished intalling in my truck Tuesday. Happy so far. Much more power than the engine it replaced or the one in the last truck that this truck replaced. I have an occasional random ~5k rpm intake backfire to figure out that I don't think is related to cam timing, but rather engine management.
I would NOT suggest using an engine flush as my low end knocking started immediately after I tried that and the crap in the oil filter was immense. I used 1/2 can of sea foam in the crank case and 1/2 in the fuel tank - I found no positive results from either.
Yeah, I've never bought into the "this can of magic sauce will fix your mechanical issue". The only thing I think that might do that is break down build up and clean oil passage ways a little, but even then how much damage are you doing to the other parts while waiting for the cleaner to open up the oil passage ways???
You can poke a hole in the oil filter and cut it open with tin snips. Easiest method I've found yet if you don't have a dedicated oil filter cutter. If you don't find metal, your bottom end is probably not hurt.
I haven't cut the oil filter apart, but I can pull off the one I have on there now to look at it.
Another likely noise causer - exhaust manifold leak on #8 port from warpage. Common problem on these engines. Have someone put their shoe sole over the exhaust tip and listen for noise increase at the front or under the vehicle.
Last night I was listening to it run with the stethoscope some more and the noise is really loud when I put it on the exhaust, but I've heard exhaust leaks on the 4.7 before and it's different than this. This really sounds like metal on metal. Maybe it's the valves, but I already took one head off and the seats we're all still good. We're going to pull this passenger side head before calling it a bottom end knock for sure.