If you are experiencing a loud (or quiet) knocking on the valve cover area of your 22RE due to lifters tapping the valve cover, I'd say 80% of the time your 4 valve cover bolts are too tight! According to other posts I've read the correct torque for the VC bolts is hand tighten and add a half a turn. Most people wrench them down tight and it causes a loud clacking in top end when the engine is running. To adjust: start engine and with a 12mm socket loosen all 4 of the bolts thus decompressing the rubber bushings and listen for that noise to disappear. Voila! If this didn't help, you may need to adjust your valves (.008 intake, .012 exh). I dealt with the loud diesel sounding noise for 6 months before I tried loosening the valve cover to 5.5 in. lbs. and the moment the noise went away I did a happy dance. I couldn't believe how simple a fix it was Sounds like a new engine now and I have 234,000 on it.
Just thought I'd share as I'm sure this is a common problem people have and deal with.

 

Thanks! I'm wrapping up my new head install this week and will try that

Do the lifters actually bang against that valve cover - seems strange they'd make the tolerances that close, especially when the cover is resting on a 1/4" tall grommet/gasket between it and the head?

 

I'm not 100% sure if they actually hit the VC but it sure sounded that way. It could have been the rockers hitting the baffle at the top. What ever it was it was loud as could be and now it's finally quiet again. The noise started after the mechanic down the street replaced the timing chain and guides and did a compression test on engine and replaced VC gasket. He appologised when I got it back and said he did everything he could and couldn't figure out how to make the noise he created go away. I decided to do some research and this method worked instantly and easily. I am new to the world of doing work on vehicles myself. I'm learning as I go. But, in my research I gathered that a lot of 22re engines make this tapping noise and wanted people to know that there is a fix. Apparently, the Valve Cover doesn't need to be that tight.. Who knew?