Brian, My first thought is that this sounds like carb ice. Your problem comes at partial throttle, and at a certain interval. The engine has just enough time to build a little ice in the intake tract, slowing closing off the fuel air mixture, then the engine gives a little cough because it's lean, which clears the ice, and the mixture comes back to normal and the process starts all over again. If it runs best with a little carb heat, then run with a little carb heat. What do your plugs say? They may show a slight lean condition.
> My engine has been running pretty smooth except for > a fraction of a second stumble about every thirty > second to a minute. During a cross country last > week at 8,500' it would give me the little stumble > about every fifteen seconds after I was flying for a > few hours. It isn't a stumble that would make you > land, but one that you pay attention to. I have a > cockpit mixture adjustment and had it out about an > inch during cruise. The engine would run rough and > loose power at two inches out, and it would still > give the stumble and decrease RPM if it was pushed > in any more so the best I could tell without an EGT > is that I had the mixture adjusted correctly. The > oil temp is fine and the CHT was only about 280 > degrees. > > Just for grins I tried pulling the carb heat in case > there was some icing even though there was no > visible moisture and I was in Florida on an 85 > degree day. I noticed that when it was all the way > on I got the normal decrease in RPM, but when it was > about half way on the engine smoothed out, picked up > 100 RPM, and ran perfectly. > Any one have any clue what this could be? > > > > _______________________________________________ > see KRnet list details at http://www.krnet.org/instructions.html ===== Scott Cable KR-2S # 735 Wright City, MO s2cab...@yahoo.com __________________________________ Do you Yahoo!? The New Yahoo! Shopping - with improved product search http://shopping.yahoo.com
