Since my car wouldn't start I was recommended to do a valve lash test. I go out there and the number 3 cylinder exhaust side (right one) valve adjustment screw wont unscrew. The locknut moves fine but that damn screw won't move. What should I do?

 

It isn't at a limit is it? Do the threads seem to be damaged? You may need to replace the rocker.

 

was the lash off before you tried to adjust the valve.

 

yes