Advice vs pros and cons of engine flush
I've owned six 318's, a 360, a 5.9, two 383's two 400s and a 440 plus two 3.9's.
Aside from an exhaust leak (which sounds just like a lifter tick) every single one of them ticked at startup for one of two reasons- 1-low oil, 2- needs the oil changed.
If it ticks longer than at startup, something else is going on like a bent pushrod or cracked rocker arm.
What brand oil are you using and how long between changes?
I found back in the day, that despite the reputation, Castrol GTX caused my lifters to tick prematurely.
I switched to Valvoline which resolved the issue, and am currently using Valvoline syn blend 10 or 5/30 (in FL).
Of course we've all heard the stories about paraffin based oil (Quaker State)causing sludge build up.
BTW I run 5,000 or more miles between oil changes.
(and have never lost an engine due to oil breakdown)
Most times, I actually change my oil when the lifters start ticking!