Re: Timing an 850 Merc
You realize that your question has no context? You have not told us what you are doing.
OK let me guess, you are doing a link and sync on a 1973 Merc 850. Am I close?
You want to know why the carbs are not closed when you are trying to set max spark advance? Did you set idle pickup tiimng? That is the answer, at least for a 1973 Merc 850......
You need a manual, or better yet a mechanic.