ERA chas Chas it depends on which pressure plate you are running, 3 finger long setup I run in the .040-.060" air gap clearance. Diaphams I run in the .030-.035" range. You want a CLEAN release of the disc with the clutch pedal in. This is what I have used for the last 30+years. For the Mcleod Soft-loc thats a whole nether story. Make sure you drive easy for 300-500 miles before beating on the clutch. It needs heat cycles and not to get glazed. Try not to feather it, no riding the pedal. Breakin is as important as air gap.
Rick L