If it were a broken spring it could cause that kind of tick, but I think you
would of seen that, the only other tick I heard like that in another engine,
although it sounded more like a rod, was a valve seat that worked loose
and was slamming home every valve cycle.
Could it be piston slap? That will knock with every power stroke, and
could possibly be checked by pulling 1nplug wire at a time, just make sure
to ground it so you don't mess up an ignition module
Wild