weired engine problem ... plz help (long...) (archive)

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I'm having a very strange problem with my engine. It's a real long story and anyone who doesn't know about rough running M20 engine needn't go on reading despite he is really interrested.

Everything started about 2 Years ago when I bought my first Bimmer, a 1988 320i with CAT. After some time I realized the ticking noise comming from the glove-box doesn't come from the Motronic but it's the ticking noise of the valves. So had the valve-clearence adjusted but it didn't go away. So I asked some people that know about this engine and they all said it might be a worn camshaft and/or worn rocker arms. So I decided to change these parts. To not do the work without any additional benefits someone told me to take an used 323i block and combine it with my 320i Cat Head and Motronic. This would increase displacement from 2 to 2.3 Liters. I did this, rebuilt the block completely from scratch (wasn't that cheap), cylinders were drilled and honed, new bearings, crankshaft pistons flywheel precisly hevy-weighted. Block built together. Then the head got new camshaft and new rocker-arms. Everything built together. Started the engine, no problem, but the ticking noise was still there. Additionally I noticed it was very rough running when at operating temp, but running smooth when cold. The very strange thing about this is that it seems to be something mechanic that makes the engine running rough because when I'm driving at high speeds in 5th gear i.e. and then releas the throttle completely so that there is no more fuel injected it is still running rough, roughest when coming down to about 3900 rpm. Can't be electronic or injection or ignition because even when coarsting (I think thats what it is called when releasing throttle so that tere is no more fuel injected).
I asked lots of people and changed a lot of little things including trying different oil viscosities from 0W40 to 10W60. Nothing helped out. So about two weeks I decided to put a totally new cylinder-head with all the part (valves, cam, rocker-arms, everything) on it because the valve ticking didn't go away and there was a relation between the rough running and the valve ticking (when engine is cold there is no ticking and engine runs smooth, when getting to operating temp ticking gets louder, hearable inside the cabin during ride, and engine gets running rougher). But now with the new head it's still the same procedure: smooth when cold and rough when warm, ticking again comes with rough running engine. Sounds definatly like valve noise coming from cylinder head.
And now the strangest thing about it: About twice or so (with the old head, haven't the new one long enough) during the last year the engine suddenly ran smooth as I wanted it to be without having changed anything. Could rev up to 7000 without any vibrations. But both times it only lasted for abot ten minutes then the rough vibrations came back together with this ticking valves. So it't can't be anything mechanical like worn bearing or cylinders. I still think it has something to do with valves/camshaft.
Any ideas? I'm on ICQ # 58844285, perhaps I could describe it better in chat.
I really did anything to make this engine run excellent but it still doesn't work. Don't know what to do...

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