Are you sure you don't have mechanical lifters instead of hydraulics?
Your symptoms sound like the lifters are either solid or are bottomed out becuase they are either owrn out or do not have enough oil pressure to pump up.
I disagree about the ful turn on a hydraulic though. Only with the factory or replacemtn lifters should you pre-load that much. With most aftermarkets a 1/2 turn pre-load is ample. When you pre-load a hydraulic lifter you are setting the lifter internal valve or piston in the center of it's total travel and with most aftermarket there is only one turn of travel full travel.
Ed