I have to mention this trick that is shown here by SurvivalBusDotCom on Youtube. Simply take a small hobby magnet, place it inside the spark plug socket where the tip will fit in and it will help keep the spark plug from falling out and into the tin on your Volkswagen flat-four. Things can be tight when working on these engines, but with a few tricks and good technique to feel your way around you’ll be tuning up your bus with less stress and more confidence. This has been an invaluable help for me at tune-up time. You’ll also need several extensions to get down to the plugs, I even find I need to use a different combination of extensions on certain cylinders due to the configuration of the engine. If memory serves I think it’s number 2, but number 3 is generally recognized as the tricky one, but not impossible. Don’t worry, with a little patience it can be done. Some people like to remove the air cleaner for extra access (’73-79.) There is no upper hatch for the first year of the flat-four in 1972. Recommended spark plug change is 10,000 miles, but I suspect many owners like me put in new ones more frequently. For more on the Survival Bus check this post.