In all honesty, the 1.5 : 1 offset rocker was probably Speedwell's greatest invention, or should I say best idea! They increase the performance of an engine by increasing the effective lift of any camshaft while at the same time increasing the effective overlap. These original Speedwell ones (check for the little "S" in a shield on one side) worked very well but, when used with a Speedwell Alloy head and the appalling Speedwell valve guides would lead to premature guide breakup and possible total engine failure!

It was for this reason that Speedwell Rockers were totally spurned by the modified motorist, making these items very difficult to find nowadays. Another alarming aspect to these rockers was Speedwell's tendency to BEND the rockers to make them line up with the top of the valve, although this practice was a little brutal, it does not appear to have negatively effected the performance of the rocker itself. It does make them look a bit odd though!