> Sam Spanovich wrote: > > >>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. > 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.<< > The best place to troubleshoot this was while you were flying, although if it was “three-cylinder scary”, landing was the thing to do. It may very well have been detonation, especially if one cylinder had a skyrocketing CHT. That’s where multiple CHT probes become invaluable...one glance and you know what the problem is, and what do (lower the nose and reduce power to barely maintain altitude) to cool it off ASAP. Been there, done that! This is the perfect argument for one CHT probe per cylinder. As was mentioned earlier, what may have made this flight different was an increased load from the new prop. No reason to trash the prop though...the engine or its tuning is where the changes are needed. I assume you were running 100LL, but if not, that change alone may fix it, or at least help define the issue better on a future flight. If it was a hot day or it heat soaked a bit before takeoff, vapor lock could have fed it a very lean mixture, regardless of where the mixture knob was. An O2 sensor would tell you that at a glance. Instrumentation can be a lifesaver, and is far cheaper than fuel. Sticking valves would not be my first guess. > > Mark Langford [email protected] >
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