Piston slap, I am not familiar enough with the inline 6's to know if it can happen (it might not due to geometry, not sure if they are a totally squared motor or not). but with most v8 if you clean up just one cyl a bit with a hone or due to high milage the rings/piston can have a slap sound called again piston slap, in the old days mechanics would knurl the piston on a cheap quick rebuild but this often caused slap after the knurling wore down. This tick can at times get a little quieter after running for awhile or right after an oil change due to the new viscosity of the oil but always returns.
