I recently put a new head on my motor (ported/polished)

Prior to the install, there was a lifter tick from the motor, not bad, but noticible.

after swapping heads, and having water in the first batch of oil, 2 of the lifters would not pump oil and were clacking bad. So we tore apart the motor again, put in 2 new lifters (all the others were good to go, oil and minimal noise).

Now the motor is still clacking, just from one of the new lifters. All 8 are pumping oil, nothing visibly looks wrong, rockers are torqued to spec and the pushrods are correctly sized and are installed correctly as well.

My question is, what gives? Me, my dad, and my mechanic all agree that everything points to the lifter should be quiet and everything good to go. The car runs great (the little slop in the lifter is making it hesitate at low rpms in high gears), idles like brand new, not burning anything other than air/fuel....

My mechanic suggested that theres air in the lifter, making it squishy still and that driving it out would eventually fix it, but im not sure, I put 150 miles on it yesterday (babied it) and still some noise, quieter when the motor is cold.

Should i start worrying about the cam? there was no signs of even regular wear on the lifters, and we looked at all of them, so im sure the cam should be fine. Im on a tight budget, so taking it in right now isnt an option, not for a few paychecks anyhow.

any suggestions on what to do here? I do have 1.6 ajustable rockers that I can put on if its a good idea, because I know I can eliminate the lash with them, but is it a good idea?

any help i appreciate! thanks!

Have the same lifter clicking sound but it is actually in the lower end near the harmonic balancer end of the motor.
Put your hand behind your exhaust pipe and see if the pressure feels the same or there is an occasional puff or out of rythum exhaust note.
Best bet, replace all lifters but before that have your cam checked to be sure it hasn't got a flat spot.

there is an out of rythm note from the exhaust. Im sure hte cam is ok, because the old lifters dont even have signs of wear on them... im taking the car in to my mechanic to have a look see at it on sunday. Im thinking the rest of the lifters should probably be replaced, thats no biggie.

I dont imagine it being anything too serious. haha and if its a cam, all the reason to get one that makes some more power .

thanks for the info so far