Help diagnose knocking issue VIDEO

The sound is like a very loose timing chain slapping the inside of the timing cover, but a bit low toned for that, and the engine is running pretty steadily. Does not sounds much like a rod bearing; too erratic, too rattley, too rapid, and not regular enough. But if lower and further back, then I would first go for a loose flywheel or flex-plate bolts, a bad piston pin, cracked piston skirt, or possibly a cracked crankshaft. The regular tapping sounds like an exhaust leak, burned valve, or a valve not seating well.

There are a number of things to check with the engine in the car.

1. Pull the bottom transmission inspection plate and check carefully in there. Look for any looseness of the flexplate/converter, or flywheel.

2. Put a bolt into the threads inside the crank snout (3/4" x 16tpi x 2.5long, with flat washer), or use the fan and belts, to turn the crankshaft back and forth, with the distributor cap off and watching the rotor. It out to reverse back and forth with very little movement of the crank if the chain is tight; if not, and the rotor does not turn for some number of crank degrees when you reverse the direction, then the chain is worn and slack. You can observe the number of degrees of slack from the timing scale. More than 4-5 degrees indicates the chain is getting to or beyond service limits.

3. You can check the thrust bearing by pushing and pulling on the crank pulley; it should move only about .010" or less.

4. I would also double check the crank pulleys and damper.

5. Have you checked this with ALL of the belts off?