My plunger B31 is fitted with what appears to be a non-standard nut on the engine cush drive (see photo). It has two plain diameters, one to locate the spring and the other being small enough to allow the splined sleeve to slide over it if the spring is sufficiently compressed. This would allow the engine sprocket to ‘cam’ over onto the next lobe. The standard 65-2520 nut only has the one diameter to locate the spring and would limit the movement of the splined sleeve to the end of the spline on the crankshaft. This would not allow the sprocket to ‘cam’ over. My question is: with the standard set-up should there be sufficient movement of the splined sleeve to allow ‘camming’ or should it be limited by the nut?