I have now seen an actual full size engine that this model is scaled from.
I noticed the 'big end' lubricator is actually mounted on the 'con rod' forward of the bearing, not overhanging at the rear as per model plans.
I wish to reduce the risk of being "clobbered" at this area but finding it hard to shape a suitable guard.
I have moved the lubricator to the rod. Added a standing vent pipe to the fuel tank cap.
This has actually helped the running balance (less vibration) and reduced the fuel leaks from the tank cap when moving the engine.