as long as you know the clearances of inlet and exhaust plus know which is which eg; inlet / exhaust, all you need to do is very slowly turn the engine over whilst watching the valve tappet go up and down, you need to find the off rocking point of this valve where there is stationary movement, meaning the valve / tappet is in a no mode move = freeplay. this is when you can adjust this particular valve to the required setting.