Knock noise

Sorry to be the bearer of bad news but converters will not be a constant even tempo tapping like that especially if it gets faster as you apply throttle. They will rattle some and can thunk if the internals have failed but they don't sound like that. That is internal engine parts making that noise. Most likely a bad rod bearing. The good news is that you could check them and even change them out if the crankshaft is still okay without pulling the engine. You just need to unbolt the mounts and jack the engine up to get the clearance needed to get the pan off. Then you could check the clearances in the rods and mains. Before that though I would get a mechanics stethoscope and give a listen top and bottom to verify it isn't something cam related, it doesn't sound like it is but before you made a decision to tear it apart I would check it close.

I agree with Steve. This sounds like an engine knock. One thing I would suggest is changing the oil and seeing if there is metal in it. You should be able to drain it into a clean pan and then swirl it around to see the bottom.

You can drain it through a clean white rag as well. However, draining it into a pan and then pouring off the top part so you can see the bottom of the pan is the best and easiest way to see the metal flake as it will go to the bottom of the pan.

https://www.2carpros.com/articles/how-to-change-engine-oil-and-filter

If there is metal in the oil then that is coming from the bearing faces. Unfortunately there is no other repair then to take it apart and replace the bearings as Steve mentioned.

Below is what bearings that are worn look like or worse they have grooves cut into them which means the motor was only a short time away from locking up.

Please let us know if you have questions on this. Thanks

If the rest of it is good and it sounds like the rest of the engine is okay, I'd probably open it up, measure the wear and see what it looks like. Then if it's just the bearing and the crank measures okay, I would likely just toss new bearings in it and run it. From there it depends on how far you wanted to go, a complete rebuilt long block runs about $3,000.00 with a warranty. Rebuilding really depends on the machine work needed. If the bores are good and just the crank needs turning that would save a lot of money.

Please return when or if they tell you what they find. No rush.

Doubtful given the location of the knocking and how loud it is combined with the tempo. Timing chains usually rattle as the links drag on the case. However that is why I said to get a stethoscope and use it to listen to the engine. You can hear where the issue is that way. A fast way to check without doing much would be to pull the plugs one at a time. If the sound stops or gets much less on a given cylinder you know it's rod knock.