The heel of the lever was designed for an ideal air gap of .038"
JP is right on with the max of .055" to .060" when using the OEM standard springs or the optional Gold .085" wire springs.
For a softer engagement you can set as low as .020", which is where we start when using for a jackshaft application.
The standard floater on a off the shelf unit is .095"
There is a .010" shim available and floaters are readily available in .090", .095", .100", .105", and .115"