G'day Ryan, I have this curse, I can't walk past a dead engine! haha! but there is a serious side to this, for,when this throwaway consumer society crumbles these skills will be so important in keeping the wheels turning!
G'day mate, loved the videos. I served my time as a fitter/turner in the mid 60's and those craft skill have taken me around the world. Sharing the little tricks we pick up on our journey's is so important, hey?. Love the valve leak test, I use diesel instead of solvent or gasoline and also ensure the ports are visibly dry before starting the test. When cleaning off the block or barrel face and the cylinder head face, I place my abrasive sheet on a piece of toughened glass and using a figure of 8 motion move the head over the abrasive, this ensures that the face remains true and flat, just adding my spice to your cake. Would be great to have aforum where us old tinkerers can share these little tricks hey ?
Just from the first video here and what you said it's possibly just valve guide seals letting the oil get through and it's just burning it off making it smoke which is one possibility obviously there's many many more