I finally got my NAA going. Carb fixed so not sucking air any more,carb adjusted, Timing good at idle and high idle, compression at 90 psi on all cylinders, valves adjusted to .014 and .016. When running the tractor it just sounds like there its running ruff. There is a rain cap on it and every so often the cap will open all the way up and come back down. It just doesnt sound smooth. It runs good though. I have never heard one run before so idk if this is common for these tractors? Any help? I would like to get the hood back on the tractor and start playing. I took a video in case any body would like to listen to what its doing. Thanks..