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A customer brought a car in that had some pretty bad lifter noise. Other than that, it would start and run reasonably well. After adjusting the valves 3/4 of a turn past zero, the car would hardly run at all. I noticed that one of the set screws inside the poly-lock was set noticeably higher (the poly-lock was screwed onto the stud more than the others). I re-set ALL of the valves, same running issue, same adjuster issue. The car was running too rough to notice if the valvetrain was any quieter than original. If I set the poly-lock in question to look like the others (back off the adjuster by eye), the car will start, idle, and sound as it did originally (bad lifter noise). It seems obvious that the valve was being held open causing the poor running condition. I am 100% certain that the pre-load was set to 3/4 turn past zero lash. This would lead me to believe that the lifter is collapsing and staying down prior to adjustment, then pumping up when the engine is running and holding the valve open. I have never experienced this before. Is this a "collapsed lifter" or something else? Does the lifter need to be replaced or is there a way to save it? Here is the combination...

3.8L Buick V6 (Grand National)
Chapman Stage 2 Heads
Hydraulic roller camshaft (~224* @ 050 range, unknown lift)
Morel (we believe) hydraulic roller lifters
Scorpion roller rockers on 7/16 studs
Poly-locks that came with the Scorpion rockers
Unknown valve springs, steel retainer
 

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Probably get more traffic in the n/a section. I do believe Morel takes a spec oil, but i'll defer to the experts.
 

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With regards to the Morel lifters, I run a hydraulic roller and initially had set the pre-load to 3/4 turn past zero lash w/ 10W-40 synthetic oil. With that setup, the obnoxiously loud ticking noise drove me nuts. I then set the pre-load to 1-full turn past zero lash and changed to Schaeffer's Micron Moly SAE 30. Results: The noise decreased considerably to what I would call a "normal for Morel lifters" ticking sound.

Of note, during the setup process I did experience pump-up/bleed-down issues with a few select lifters. I had to rotate the engine a few times, adjust, check, rinse and repeat, until the lifters all appeared to "stabilize" and hold.
 
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