Buddy of mine has an O-200 with about 120 hrs since field overhaul. Just bought a new Kelly Aerospace MA-3 carb about 20 hours ago and came out of annual 4 hours ago. At annual they found the #3 cylinder had very poor compression and pulled it for the local guy to go through. After annual, he flew it about 4 hours home with no problems but when he went out the next day to fly, it would not run well above idle. Found a sticking valve on the newly worked on cylinder and after some penetrating oil and time it began working fine. Ran it again and same thing- engine begins to miss/load up/ sound like crap at about 1200 rpm, and clears out around 1950. Will run up static to 2300 rpm, and mag check is normal. Checked compressions cold and all cylinders at or above 70. Checked compressions hot and all at or above 75. Warmed up and set idle mixture correctly. No change. Pulled off cowl to take a good look and found #3 cylinder intake nuts had either not been put on or had come off. Replaced and tightened intake nuts, checked the rest of the engine for loose hardware and ran again. No change. No primer installed so not that. Sprayed carb cleaner on engine intake connections while running and no RPM changes. At this point we are thinking that the new carb has a problem. I think this can be caused by either an accelerator pump, or maybe some of the idle circuits having gunk in them. Engine makes great static power above 2000rpm, and idles normally. Any ideas other than pulling the carb? The folks he bought the carb from said that the warranty is 6 months or 60 days after installation, and since he bought it in November, installed in march, they are saying he will have to pay for a complete rebuild. Any ideas? Maybe a lifter? Ignition leads? Don't think it is valve springs but since the relatively new cylinder is already causing problems who knows.
JB
JB
