Post a good sounding video of the noise..........There are about 3 major areas of tap or knock,however you may word it.
Tappin in the heads,usually you can get a clue by removing the valve covers.
Tappin deep in the block it could be a rod ,they like to click or tap ,depending on terminology.
Then there is the knock or thump sound of a crank bearing.
Most engine guys can tell you almost exactly what it is by sound ,by description a tap/tick/knock is really hard to put your finger on over the internet ,but with a video with good sound ,its almost like being right there......