Hmmm I'm thinking this might help me out as well I just pick led an 84 f150 300 I6 1bbl and t18 30k original documented miles first time ran in 15yrs ive done vaccum lines cap rotor etc. Carburetor rebuild has terrific throttle response but really rough idle ive been playing with the timing for about a week now using the bolt on plate on passenger side never noticed the second mark my manual never mentioned it either but was wondering could someone possibly post some pics of the marks lined up?? Thank you the thread was extremely informative and also are there baby other california friendly improvements I can make to my I6??