Good Afternoon all
I have just done my head re-tension and adjusted the valve clearances and as usual I use the rule of 9 like in the workshop manual. However I rechecked the settings at TDC for each cylinder and got 2 thou more on every rocker.
I have turned the engine over multiple times and rechecked everything again using both methods and found using the rule of nine I still had 19 thou clearance which was my setting but putting each cylinder on TDC firing I came up with 21 thou.
I suspect this is because of a large overlap of the cam lobes.

Has anyone noticed this before?

I've used only rule of 9 for the last 50 years.
However I only move the crank 4 times, as you can get both an inlet and an exhaust valve (nearly) at full lift at the same time.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.