what are the most commonly overlooked steps/items when building an engine? Such as forgetting to take a measurement or forgetting to install an oil plug.
Most common overlooked item is documentation. Very few people actually keep track of part numbers used, dimensions, clearances, etc. After a few months they don't remember what valve springs they used, what the bearing clearances are, what the ring gap was set at, which parts they used, etc. Then when they have a problem they have to start over.
