I have heard of removing the plug wire to each cylinder to tell if removing 1 compared to any other 3 that are still connected, would make a difference.
If there is ticking, sound resonating...and it's related to a spun bearing, you'd figure the one with the spun bearing(if there is one), would reveal a difference in the idle sound when that one suspected cylinder is not receiving spark compared to when 'healthy' cylinders are continuing to receive spark.
...by the way. I TOO had ticking sounds top-end that I couldn't quite determine where it was. It sounded like it was below the dizzy. I do have a worn clutch, and whatever related parts that may be allowing for extra 'noises' associated with such, that's been my hope for now as I hope replacing that will get me home free moving forward.
ADDED: With the mention of the ISB, which of the following is it in the following link?
Manually pushing the clutch release lever forward with you fingers while idling will tell you if the flywheel is wobbling.
Are you sure that you don't have any exhaust leaks around the manifold or cat?
I think a rod would be knocking all of the time, not just in a particular rpm range.
I wonder about really bad piston slap- almost like the pistons are really loose and rattling/tilting back and forth at a particular rpm. I get piston slap around 2000 rpms on cold mornings it is loudest under a slight load and it gets fainter as the engine warms up.
A loose wrist pin(s) might be another possibility.
If the vibration and noise are correlated, then I think it may point to a piston issue. If the crank was unbalanced, then the vibration ought to get more severe as the rpm increases more and more.
I wonder what the machinist would say if you asked to have the original pistons back- this would prove that really did put new pistons in the engine.
I unplugged the injector because I did not like the idea of so much unburned fuel going into the cat being that these maniverters are hard to find.
No exhaust leaks to speak of, I have been under with the engine running.
I also think rod knock would get worse with rpm or be noticeable on start up
Piston issues seem more likely.
I delivered the pistons myself and saw them in the block before the head was torqued. I did notice that while I was spinning the crank by hand while doing the timing belt that there was a clunking noise when the pistons changed direction but the shop said that is normal piston rock and assured that the piston to wall clearance is good.
I will check the flywheel and try to get the oil pressure but its looking more and more like I just need to drive it until something gets louder. If I'm pulling it back out I want to be sure.
Did they give you a warranty? Most junkyard engines have a 30 day warranty. With all of that machine work you ought to have at least a 90 day warranty.
If you have a warranty, you might as well drive it until it gets louder/fails or proves itself.
A quick and dirty way to check hot oil pressure is to get the engine nice and warm and stall the engine in 5th gear while stopped. If you can drag the engine down to 50 rpms and the oil light is still not coming on, the bearing clearance is pretty tight. After killing it while hot, unplug the injectors and crank it over. With a nice tight engine, the oil pressure warning light should go off at cranking speed, even with the engine oil hot (thinned oil somewhat).
Great follow up by Erik. I can see the logic now pointing towards top-end instead of rod knock, sorry for giving false-direction. I'm curious as to how this turns out, and do agree it's not worth pulling unless you can confirm what it is.
It could be wrist pins, it sounds terrible either way.