Well the good news is we finally resolved the motor not running above 3500 rpms. I posted previously about the problems that we had with the motor. We replaced the the stator trigger and switchbox because we didn't have spark on cylinders 3 and 4. That problem ended up being a bad switchbox. I recently tested with a spark gap tester on cylinders 1 through 4 at 3/8ths and 1/2 inch and it produced uniform spark to all the cylinders. The problem most likely doesn't lie in the ignition system. I have gone throught the fuel system and we recently found that the previous owner who sold us the motor had the wrong (larger) jet size. in the 4 carbs. I purchased and changed the jets the the .054 size speced in the service manual. I tested with 2 props today and was able to turn over the maxinum recommended rpm 5500 with a 19 pitch and around 4750 with a 23 pitch 4 blade. We hadn't gotten to the point of chosing the prop for the boat yet. The boat is a champion 16. 8 Bass boat, Anyway I am looking for any advice or tips on trying to resolve a rough idle in gear. it is a 2+2 motor sos the top two carbs have idle adjustment screws. The fuel lines filters are new and the carbs have been rebuilt and the reeds are new. The timing is set within specs at idle so I am thinking the rough idle in gear has to do with the fuel side. I have never adjusted the carbs for a mercury enging before and did the carb sync as best I could. The carbs are currently set at around 1 1/2 turns out on 1 and 2. Also could the rough idle come for a fuel situation at 3 and 4? Thank you everyone who got us to this point. just a little more fine tuning to get the boat back t where my dad can get some time in fishing.
