Ok to start a list of what has been fixed/done to pre answer some replies
1.Crank shaft reground and new big end shells
2. small end bearings checked and one replaced
3. reshimmed crank (2 thou)
4. New primary chain
5. valve clearances checked and set (8/10 thou)
6. All mounting bolts tightened
So now to the issue always tapping just like a to wide valve clearence esp at tickover. When accelerating sounds like small knocking but not. Can hear it as the power comes in then not as I go faster(could be masked by wind noise etc). No increase in vibration beyond the norm as in say a worn big end. Not a small end as I had that last year and it was horrible.
Took the timing side apart and took off the dynamo chain no change in noise. Levered the crank no movement. No movement in idler pinion. Removed front valve cover no increase in noise.
Ran over the engine with the screwdriver test and when put onto the rocker feed bolt for the exhaust feed the tapping could be heard/felt. So I am leaning towards cam/followers is there anything I missed??
many thanks Andy