I had a problem with my merc, it wouldnt run after i got the carb rebuilt at a shop, before i brought it there it idled fine, after i got it it didnt run, i found I had to advance the timing, it was almost 90 deg out, I took off the stock timing screw which was not long enuf and relaced it with a 3 inch that gave me more travel to adjust the timing. It runs great now but I wanta figure out Y its off that far and I want to get that screw out and replace it with the stock size. I cant figureout y its so far off timing. with the motor off and the #1 cyl top dead center it is perfect on the flywheel marked tdc...but y the hell when it runs is it so far off?? any suggestions???