The car is running ok again, the cam is timed the way it came off, TDC on crank and punch marks on cam and cam bearings. No extra fiddling or poking at funny bolts or screws. I learned during my apprenticeship to put marks on everything whether it was marked or not , just incase!! It is more reassuring during re assembly.

I just wanted to know how this 6 degrees of adjustment may be achieved, probably as Gilly says by combinations of sprocket position on the cam. Stu Ritter knows I guess!! Thanks for all your replies.

Gerard