I have had what I felt was excessive valvetrain noise for as long as my 370 LQ9 has been in my car. It has always run great, no issues at all. The engine has Morel lifters in it, and I had done some reading stating that the recommended preload for them was .030-.040 for an iron block and aluminum heads so yesterday I pulled the valve cover off and decided to do some measuring. I rolled the engine over so that int and exh valves on #1 cyl were closed, pulled both rockers off, pulled the current 7.375" pushrods out and went to town checking with my Comp adjustable lifter for proper length. I then reinstalled the 2 rockers and repeated the procedure on #3 cylinder to check for consistency. I came up with my engine needing 7.325" to get in the right range, and reassembled everything with the old pushrods until I could get the pushrods ordered. Once back together, the car didn't want to start, but finally did and ran extremely rough like it was missing on numerous cylinders. I shut it off, and pulled the valve cover back off to ensure that I hadn't done anything wrong.

Upon loosening and re-torqueing my rockers on #1 and #3, I now notice that once I hit 0 lash and begin to further tighten and torque down the rockers that the rocker is opening the valve instead of preloading the lifters. I am now at a loss for what could have happened. I guess I'll be pulling the heads and checking my lifters, and hope that hanging the valves open didn't cause the valves to hit the pistons. Anyone have any guesses as to what I've run into?

Cam is a pretty mild 227/232 with roughly .580 lift on both int/exh.

 

The lifters jacked up when rockers were off. Tighten rockers, let the motor sit for few hours, the pressure of valve springs should slowly push plungers in lifters down and close the valves over time.

 

That would make my week! I'll give it a shot and see if it does the trick.