The adjustment of the rockers with either hydraulic or solids lifters using a feeler gauge to set the lash is not always the best way to wind up with a silent valve train. The valve stem wear and shape of the adjuster can create allot more lash than the thickness of the feeler gauge. I don't think 0 lash cold is the way to go in either application as tempting as the idea has been at times. I do think that adjusting the rockers after the engine has been run hot but is cold enough to not burn the heck out of yourself is an option and one I have used for years. The solid lifter valve train can gain clearance as it warns up and the hydraulic can loose clearance. We could argue the reasons all day and some might even say the opposite happens. When you have a noisy valve with solid lifters try to find it when the engine is warm and close down the clearance a little and then run it. I would then check it cold to see if it has clearance cold. I determine that a valve is closed all the way if I can spin the push rod.  I adjusted the new 2.1 engine in my wife's van last week to 0 warm (hot) after it was cool enough to touch each rocker had just a litlle lash and I spin the push rod when the ajuster nut is tight. I will have to keep an eye on it because I want to prevent any preloading the hydraulic lifters might develop
     Stan be careful of aftermarket solid lifters most are not compatatable with OEM cams and they will wear the lobe out in as little as 2000 miles  
Bob Donalds 
http://www.bostonengine.com      
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