Through my research I haven't found an objective spec on what it should be but more less "exercise the rocker arm throughout its throw and check for interference. Provide clearance and adjust as necessary". Seems a bit generalized. I am hoping to run these HS 1.7 on my Magnum Heads but I upgraded to a larger spring and retainer combo to work with the cam I have. It brings the arm pretty close as you can see. I know a Dremel could relieve that some if need be. Wasn't sure if there was a spec for reference or something anecdotal. Thanks!