-SG- I have been messing around with Vintage Nortons for longer than I care to remember but there is always something new to discover! This time it concerns the rocker standards used on the OHV engines in the twenties - see photo. The measurement on both of these examples, from base to centre of rocker spindle, is identical. BUT the measurement from base to centre of the tie bar hole is substantially different. On the right hand one of the two, it is 2.140" and on the other, it is 2.008". Why? When? I have no idea! If anyone has an answer please let us know!