Before I get into the main point of my message, I would like to shout out to Ed Sterba at Sterba Propellers. I received my brand new 54" x 54" for my Remaster 2100D, put it on, and took N6399U for a ride. With my Culver 54" x 48", I had decent climb out but only averaged about 104-105 knots at a relatively high RPM of ~3300 rpm during cruise.
With the Sterba 54" pitch, the climb-out remained essentially unchanged at about 700-900 fpm, sometimes >1000 fpm on occasion, however the cruise speed increased greatly. My old spinner (for the Culver) did not fit the Sterba so I test flew without it, however I still managed around 110 knots cruise at about ~3200 RPM, almost 100 less than before. I am hoping once I figure out the spinner situation, I'll get maybe in the 111-112 knot range. All in all, 6 knots may not sound like a lot, but for me I was greatly impressed for such a simple upgrade. I was also impressed that the climb rate remained very similar; there was no "night and day" difference in climb that I have witnessed on most planes with climb/cruise props. NOW, for the "main point" of this message. After cruising around for a while with the new propeller, I started a descent from about 2500' MSL. Brought the power back to about 2800 RPM, put the Carb Heat On, and descended about 500 fpm back to pattern altitude (2500 MSL --> 1300 MSL, so a little more than two minutes). I arrived at the "abeam" while I was still slightly descending and slowing down, so I just left the power where it was, put the speed brakes out, and flew a racetrack pattern into short final. As I approached the runway, I figured I would try a touch and go to see how different the new propeller felt on a go around. As I ran the engine up to full power, initially everything felt okay, however as I got about 200 feet off the ground, *The Engine Started to make this God-Awful Chugging Noise with Uncomfortable Amounts of Vibration!* As unnatural as this was, *I Pulled some Power Back To About Mid Range, and the Chugging Stopped and the Engine Ran began to run Smoothly. *I continued to climb out at about 200 fpm, and when all seemed okay, I made a very gracious crosswind turn and* Very Graciously Applied More and More Throttle. *Upon doing this, the *Chugging/Vibrations Returned. *After this, I set the power to where the engine was smooth, and did not touch it until the runway was made. I landed safely, took a deep breath, and taxi'd back to the hangar. >From the time I started the descent and for the remainder of the flight, the engine *mixture was at full rich*. The* carb heat was on when I started the descent, and remained on until I added power during the go-around, when I turned it off*. Once the chugging started, I turned the heat back on and *it appeared to have no effect whatsoever. * This is why I am calling all Revmaster Owners, because.....any opinions/tips on what to look for are greatly appreciated I am suspecting it is either a carburetor problem of some sort, or worst case the exhaust valves sticking (I have done some research and it seems early model Revmasters, like mine, are notorious for this happening). I am suspecting that maybe during the descent the engine got "over-cooled" from all the ram air blowing in the engine cowling while being at a relatively low power setting (it was only 66F when I flew today). I am wondering if such a cool engine could maybe cause the exhaust valve to stick since the cylinder heads would (in theory) contract due to the cold temperatures, because during the summer months (80-90F) such chugging has never occured even when I descended at essentially idle and went to power up for a go-around. So basically, a quick recap: *Startup, Climb, Cruise* = Totally Normal: Mixture as required, Carb Heat off. *Descend* = Power to mid range, Carb Heat on, engine cooling down. Mixture Full Rich. *Pattern *= Was completely normal. Power still relatively low, Carb Heat still on, Mixture Full Rich. *Landing* = Power at Idle, Carb Heat On, Mixture Full Rich *Go Around* = Initial power-on was okay. Carb Heat off, Mixture still full rich. *Climbout* = This is where the problem started. *Power On* = Engine Roughness. Carb heat on/off had NO effect. *Power Mid-Range to Idle* = Engine Smooth. *Taxi to Hangar *= Completely Smooth Running Engine. You would have thought nothing ever happened in terms of the engine running. Upon pulling the plane into the hangar, I checked the spark plugs and they all were completely normal and not fouled. I did not check much else after this because I wanted to post on here and get some opinions first before I went looking in the wrong places. But my instincts are telling me to look at the cylinder heads. For reference. This is the 65HP Revmaster 2100D, stock cylinder heads. Revflow Carburetor. Any help is greatly appreciated, and I really apologize for the long message. Thank you all very much, and safe flying to you all. V/R Sam _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org
