[cotbu]

From the exhaust it does sound like rod knock, a lil, but it also sound like timing. Go to the front of the engine and listen with a screw driver etc. to your ear. for us, the camera, rev the engine to 3krpm keep it steady also remove the oil cap, it lets the sound out.

you can try the slack test, by rotating the engine past tdc for each cylinder and push down on the piston. listen for a clack and feel for any movement.