There is a 4 degree offset Key that you could install to take that up. However, you need to do the 2mm method with a dial indicator to get a definitive reading.

Also there has been others with that approximate 5 degrees that did not have the symptoms you are having.

Note that in the manual it has that after the first 20000 mile on a new engine it is normal to have 2.5 degrees of timing chain stretch but that is using the 2mm method.

I think if you installed the offset key what you would find is that the symptoms improve slightly but it is your Fuel Injection pump timing or some other reason that is causing the white smoke.

So the offset key is a cheap and minimally invasive method of finding the actual cause of your issue.

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84 300D, 82 Volvo 244Gl Diesel