The spacer was added to pull the carby away from the engine. As Victa found that because of where it was it was causing evaporation in the carby and stalling the engine. I'm not 100% sure (as there is no paper work with this to prove this theory) but it is believed that they were installed after they were sold. Put on by Victa mechanics during a service,(as the theory goes),but don't quote me on that. In saying that that's what they are there for anyway.
