I set mine on my J whilst the engine is warm as the stock tensioner will extend to the slackest point anyway. From my original post: -
"Anyway, so that I don’t become obsessed with camchain tension I spent a bit of time tonight checking it when cold having set it when hot last night. Resetting it cold was maybe two flats further out on the bolt, which is quite a coarse pitch. So, I then spent a bit of time setting it whilst warm and running at a constant speed (about 1500-2000rpm), where I got it to a point where you could feel the chain running against the guide through the tensioner bolt, but if you rocked the bolt gently you didn’t feel it. That’ll do for me!"
Thread here: -
viewtopic.php?f=4&t=43226&hilit=Tensioner