Sounds like you did not have the special of home bent Valve wrenches and to start off with did not remove the Fuel Injection Lines.

For the bottom nut you need to either thin out a wrench or find one that is thin. The special Hazet Valve Adjusting Wrenches have a thickness = 0.242; close to 1/4 of an inch 0.25".

Also the first time you do something can often be the worst and you started off without removing the Fuel Injection Lines.

It is hard to tell from your description if the Valve and Spring Retainer were rotating or not when you did your adjustment.
That happend to me on the first Valve Adjustment but I had that 3rd Wrench. However, in the threads there are several methonds of holding the Valve Spring Retainer to keep it from rotating.

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84 300D, 82 Volvo 244Gl Diesel