on a centrex clutch you adjust a nut that tightens a spring once you to that you shim it so you have enough gap between the clutch and the clutch bell. you want some play between them if you don't have enough then your engine could overheat.
you use this tool to turn the spring nut
http://ashfordhobby.com/detail.aspx?ID=424
i had someone else at the track adjust my clutch basically you use this tool to measure how far back the nut is
http://www.kamikazercracing.com/prod...php?prod=TTCT2
if you can get you manual it should tell you how far the spring nut should be.