Cam bolts into 66-84 (except 80-81) Big Twin engines with no head work; on 80-81 engines the height of the stock H-D valve guides restricts spring travel (and cam lift) to .430" or less Spring travel and clearance, plus clearance at main bearing boss must be checked on 80 and later models More mid-range and high-end power; idle unaffected. CAMSHAFT A2 70-77
