Ask ten different mechanics and you will probably get ten different answers as to the proper way to set valve lash. The following is the ONLY way to do it, and I will accept no argument to the contrary!

We are dealing with mechanical cams here, If you don't know how to set up an hydraulic cam then you have no business reading this. Mechanical cams require "LASH", hydraulic cams require  "PRELOAD"

Aside from the obvious such as proper assembly of the engine, and proper degreeing of the cam etc. Setting the valve lash is THE MOST IMPORTANT aspect of your engine. By experimenting with various lash settings you can actually see how different grinds will behave in your engine. You can stagger lash values and find out what your engine likes.  The main problem that most people have is getting the valves to stay set once you have the lash setting you want.

We check our valve lash after every pass in our dragster, we RARELY have to make any adjustments because we set it right the FIRST time.

No matter if you use regular poly locks or a shaft mounted setup such as a Jesel system the method is exactly the same. The outer nut on a poly lock system is used to adjust the lash and the set screw is used to bottom out on the top of the stud and lock the setting. The use of a stud girdle sometimes requires a slight compensation in the lash setting . You will have to check this out for yourself to find the optimal setting.

The method of setting your valve lash properly is so simple that to do it any other way makes no sense to begin with.

The lash must be adjusted when the tappet is on the heel of the cam lobe. Remember that this is the lowest part of the lobe, hence the tappet is as far down in the bore as it will go. You can't see this when the heads are on, the way that you determine when the tappet is in the proper spot to adjust is as follows;

Adjust the Intake valve lash when the EXHAUST valve begins to open, this will assure that the intake valve is on the heel of the intake lobe.

Adjust the Exhaust valve when the INTAKE valve has just closed. Your setting will not change if you do your valves this way.

Re-read the above two sentences and you will see the beauty and simplicity of this method.