Distributor shaft length

cap off, install rotor & retract it all the way (if the weights ain't stuck the springs should already be retracting the weights (rotor). move housing to line up the magnet with the nearest tooth. snug down dist. make a mark on the metal dist housing rim plumb vertical down from the rotor location. install cap. make another mark on the dist top rim just below the CL of the cap bulge. take off the cap & see how far they are from each other. use the pickup that gets em the closest. the rotor has a wide blade and the cap terminals are wide so you have alot of leeway before the distance becomes too great for the available voltage to fire that gap. NAPA has an Echlin rotor with a .060" longer blade (MO3000) for $8 & change out the door or you can easily drill one out & add a longer blade your self (.015" clearance is ideal) this radial clearance reduction helps with the circumferential circular distance around the arc (they both add up). Note that vac adv will shift the phasing CCW on a SB from the at rest (no vac) position and an 8 deg (stamped) can will shift the rotor blade tip 8 degrees at full vacuum (cruising) or actually anywhere above what it takes to max out the can. the rotor will swing in an arc & I like it equidistant on either side of the cap terminal & definitely closer at WOT (no vac) in a perf app (when required voltage is the greatest)