I am working on a 1990 4.3 in a forklift.i pulled the heads to be rebuilt.when putting it back together doing the valve adjustment i Followed the procedure of twisting the pushrod and then going one full-term after it gets all the lash out of it I can't get a full turn out of it the nut runs out of threads on the studs I thought maybe the studs were pulling out but they're not I'm kind of confused by that if I run them down to where all of them not stop the valves won't close all the way so now I'm lost I don't know why it's giving me problems maybe the lifters are bad and they never made any noise in the past.I've been a mechanic for 26 years I've never had this problem any help would be greatly appreciated thank you

 

Welcome to the forum. Need to ask your question in the correct section of the forum as this is just the Welcome section, not for hslp.