So I'm trying to diagnose a bad idling problem with my '78 280slc and decided to check the cam timing. With the engine at TDC the intake cam lines up perfectly, but I'm not so sure about the exhaust cam. I don't know how precisely they should line up, so I took a picture. Do you think it needs an adjustment or is it ok? To me it looks a degree or two off.

Thanks.

PS: nevermind the oil buildup, this car had a rich running condition for quite a long time, but it's fixed now.

EDIT: please see post #3.

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A slightly retarded exhaust opening point will not be the cause of "a bad idling problem", whatever that may be.

Let nothing you dismay; if you wish for folks here to provide help, have a go at describing the symptoms of the problem!

You're right. Sorry for holding off info, but I'm soo deep in this that I'm on the verge of insanity, so here it goes...

My Euro '78 280SLC has this weird problem: The car runs great, as long as I don't exceed about 4000 RPM at full throttle. If I do, the car start to miss fire on one, and sometimes two cylinders at idle and up to about 4000 RPM. If I then proceed to turn it off for about 30 minutes or so it start right up and runs fine again.
Also, there is an accumulation of oil inside the intake manifold in the form of a 2mm deep puddle. I have no explanation for where it is coming from, as there is no blowby (the breather on the valve cover actually has a little suction).
Other symptoms include:
-Slight oil fouling of the plugs, but no blue smoke or blowby;
-Manifold vacuum pressure at idle of only 14inHg (no EGR or other smog devices);

Things I have done so far (in no particular order);
-Adjusted valve gap (0,10mm intake / 0,25mm exhaust);
-Changed spark plugs (NGK BP6ES gaped to 0,8mm);
-Changed leads, rotor and dist. cap;
-Replaced the coil;
-Adjusted ignition as per workshop manual;
-Checked injection system for correct pressure, and eliminated both the fuel distributor and the WUR;
-Played with the mixture screw more times than I can remember...
-Checked for vacuum leaks (found none);

I just did a dry and wet compression test with the following results (valves were adjusted only 3 days ago):

Cyl / dry / wet / difference
1 - 120 / 130 / 10
2 - 118 / 135 / 17
3 - 120 / 132 / 12
4 - 122 / 135 / 13
5 - 122 / 135 / 13
6 - 122 / 135 / 13

If I have ring or cylinder issues, shouldn't the difference between wet and dry be a lot higher then just the 13 psi average that I've got? Or am I looking at an engine rebuild?

Although cylinder wall condition and ring seal would appear to be good, the odds are substantial that at least two intake valve guides are loose in the head. They are the source of the oil in the manifold, and will cause an air leak and/or hold intake valves slightly out of position on their seats until everything cools a bit and they return to their intended place.

I was kinda hoping it to be valve seals, not guides.
I've heard about this issue on M110 engines, but can't remember what the appropriate course of action was. Should I look for a replacement head or is this something that a machine shop could fix?