Sometimes when the valves are too tight for a while, carbon builds up on the valve stem (intake in particular) and this will cause the valve to go tight again when the carbon wears off after adjustment.

I'd check again in about 1000 miles. If any are tight again, leave them loose (0.010" more clearance than specified) for another couple hundred miles, then set correctly. This should get rid of any carbon buildup. If they still go tight, set them loose again and repeat.

Too much clearance will give you lower performance and more valve train noise, no other problems.

Running with them too tight will erode the valve and seat. When this gets really bad, you will need to do a valve job. Time will tell.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!