In my new /6, I've noticed what seems to be excessive valve train noise with my 268 purple shaft cam. I have the lash set at 18 on intake, and 23 on exhaust. I've checked it, but it sounds like a few rockers have more lash in them, maybe from a worn bushing bore? Is this a common problem? I know what the valves sounded like when I had them set looser for break in, and that's mostly quieted down with the tighter lash, but it sounds like a few rockers are still noisy.

You know I don't like that MP .268ºcam for just that reason, always has lot's of tappet noise.
How are the rocker arm pads, any ware? (if there is any "dent", resurface the pad) Also be sure the tips are centered over the stems. If there is any off-set in this area, it increases the arm rocking and the noise.
Keep playing with the lash, go a little tighter, especially on the intake side. "sneek down" a little tighter, this will make the engine think it has a bigger cam. you are getting close to the limit on the exhaust side but if one or two of those are making the noise, try tighter but if the idle starts getting real rough, back-off, noise is better then burnt valves.
Let us know what you find.
DD

My experience with "shimming" stock rocker stands is you tend to loose oiling capacity. make sure there is enough oil coming out of the squirt holes in the rocker to lube it and the valves.

beardliz@msn.com

I made sure that the rear shim had a big hole in it. No problem with getting enough oil to the rockers.