I have over the last 2 days read every post on this forum concerning 447/503 overheating issues. I have an issue that is perplexing and that no one I know can give me an answer on. My 447 which was brand new when I finished the plane  (Kolb Firefly) and now has 320 hours on it. Over the years I have experienced temp. differences of up to 150 degrees higher on mag end than on PTO end. The last couple month's of this flying season it started to go over 200 degrees difference. Here's all I've done--- Less than 10 hours ago I installed new rings and all upper gaskets. No change. My CHT's are always good, 300 -350 and never very more than around 20 degrees. I have assumed that I am sucking air on Mag cyl. somewhere is why I replaced all upper gaskets recently. 2 winters ago I replaced the crank seals -- no change. At this very moment I have the engine under pressure and with a little over 10 PSI it has held all afternoon, 4-5 hours now. I have switched the probes dozens of times over the years and the temps follow the cylinders every time. and the temps read about the same on the opposite gauges as they did before the switch. My plugs always look the same in my opinion, I have decarb,d probably 4 times and the condition of cylinders and pistons always look equal to me. It is single carb so I don't see how 1 cylinders piston moving up & creating suction in the crankcase can pull in any more fuel than the other to create a lean or rich difference. I am at a loss. I am trying to attach a few pics for clarity. Any help appreciated  ------- Rick Fraley, Eaton, Ohio.   



You do not have permissions to reply to this topic.