Mmmm striped the engine and found not 1 or 2 bent rods which was my guess before I pulled it apart but 4 yes 4 bent rods
Will never run one of these things without a catch can again went for several years with no probs until I went to the track for some fun.
On the subject of the heat soak have had an initial meeting with Sprintex re my cooling idea so should know whether that is going to progress to the test stage
or not in the next week, they seem reasonably interested but early days .