If you try to do it without the valve lash tool then you have to keep rechecking it as you tighten the locknut, pain in the ass. Buy the tool or make one. I welded a 10mm deep socket to a 11mm deep socket and then welded a long bolt to the side so you can apply torque. A long screwdriver fits through the middle so you can hold your setting in place while you tighten the locknut.