What to do about a ‘slightly’ rough running engine

I always look forward to hearing what you have to say, so here is my question: I fly a 1954 Piper PA-22/20 with an O-320 (no suffix) Lycoming, with about 975 hours since major. I fly it 150 to 175 hours per year, and keep up with all the maintenance an old ship requires. The engine runs beautifully, takes about 1/2 quart of oil between changes, has no leaks and has good compression. However, when I pull back the power for a long descent (2,300 to 2,100 rpm), I get a “”slightly”" rough running engine. If I reduce further, to 1,500 or so, it smooths out. I had the prop statically balanced at a reputable shop and it seemed to help a little, but I was wondering if dynamic balancing would be the next place to look, or is there another direction?

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Is a factory rebuilt engine reliable?

I probably will buy a C-172 with a new — actually rebuilt — O-310-H2AD engine. Do you know if this engine is reliable? Does it meet the latest factory changes?

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There are no stupid questions… Just unusual ones that, unfortunately, don’t have the desired answer

This seems like a stupid question but I’m going to ask anyway. Did Lycoming ever have a service kit to put hydraulic lifters into the O-235?

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How do I install an oil cooler on my homebuilt?

I have an O-235 Lycoming engine. The assembly case has not been drilled to accept an oil cooler.

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Which valve is safe to use?

QUESTION: I have a question on my IGO-540-A1A, an engine with a rated RPM of 3,400. When it comes time for an overhaul, S.I. 1037K calls for intake valve LW-12949.

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Prepare your plane for winter

For those of us who reside in northern climates, it’s time for us to begin thinking about what we need to do to get our aircraft ready to put in the barn for the winter.

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Should I lean while taxiing?

QUESTION: I have had instructors insist that I lean the engine while taxiing my O-320 Lycoming.

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Can you identify this engine?

QUESTION: A friend has an O-320 in his hangar. I have only the following data, and am wondering how or where I can use these data to determine exactly which engine this is. Data plate says: O-320, eng #2689-27. The case is cast with the number L-17001-27A. I tried using the Lycoming website, hoping for a serial number lookup table, but so far no luck.

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Can I use a yellow tagged camshaft in my Wittman Tailwind?

I have a Lycoming O-320-D2A that will be going into a Wittman Tailwind. The crankcase and crankshaft are yellow tagged. The camshaft is really pitted and will need to be replaced. I imagine the followers will need replacing also unless refurbishing them isn’t a big deal.

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What’s causing popping noises at low RPM?

I have a high-wing homebuilt aircraft into which I have installed an IO-360-A1B 200-hp Lycoming salvaged from a Lake Amphiban, with 660 TT. My problem is that it makes loud popping noises at low RPM, such as when landing or taxiing. I have a cross-over type exhaust, and have had a mechanic check both the exhaust and the intake for leaks, but this is not the problem. Do you have any idea what else might cause this problem?

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