DS1980

Lean first and then play with the throttle and carb heat at the offset of roughness. The idea is to mess with setting because the engine is starting to run rough, not make it " more smooth" since there isn't such a thing. This also gives a hint about where your EGTs are at in case your gauge is inop or the airplane you are flying doesn't have one. Remember too, its all about CHT.

I like kittens. There, now at least Mike's post was about airplanes.

This is entirely possible for a specific engine set up. I would have to say overall, and the LOP pioneers agree, that best economy happens around 50-75 degrees LOP. The real question is that does-for YOUR engine- 15-25 degrees LOP keep your CHTs within range? You're one of the more experienced pilots on this forum with regard to LOP operations so this question is rhetorical for you and a case in point for others new to this LOP silliness.

Awesome! Add 1 to the LOP Revolution!

Yes, if you are operating your engine properly, you will replace your engine due to rust, not engine wear. Most pilots rust their engines out, not wear them out.

It does. As you stated it "turns off" the enrichment valve ( the Brits call it the economizer, which sounds better) and creates some turbulence in the carb. If you've ever sucked through a straw with a hole in it you can get an idea of what is trying to be accomplished.

A perfect execution with a not perfect result. It was worth a shot Hank!

The use of carb heat and throttle positions are the only methods I know of. Doesn't mean there isn't more. The idea is to maximize the atomization (wow, sounded smart there eh?) of the fuel so that when it enters the intake manifold all of the fuel molecules weigh the same. It won't be perfect, but then again even balanced fuel injectors have a margin of error (I think 0.5 gph). As I stated as well at Byron, keeping the power at or below 65-60% the engine just isn't generating enough ICP to hurt itself.

And I agree with everybody Aaronk25, put the name on here. Why protect the guilty? A mechanic will pass his biases onto customers: "Oh, this guy runs lean of peak. Guess I will have to charge him for new exhaust valves. Oh, lets throw in a cylinder replacement too. My borescope broke but I know it's bad."

You're talking about balance, and that's true. The subject was running rough in regard to fuel distribution. And a single cylinder will run wonderfully in between too rich to burn and too lean to burn. My lawn mower, weed eater and model aircraft engines are proof. All single cylinder, all run like a top in between flooding and being starved. I agree that some vibrate because there are no counteracting forces. This is vibration, different than rough.

No worries. It's hopeful though since you were so close without using carb heat or closing the throttle plate a little. Just check your POH for power settings that keep you around 60% and you won't hurt anything. 350 degrees for your CHT is excellent. How far apart are the cylinders when it goes smooth at 8 GPH? What power % does the POH say at the cruise settings you use? I'd be careful with the whole lean-to-rough-and-then-back-to-smooth OWT. Of course if you're at 370 degrees you might be ok. But the 350 is better.

No MMO. Camguard only.

A thought on roughness--Lets take a simple single cylinder engine. A single cylinder engine will not run "rough." It will operate just fine throughout all of the mixture settings between too rich to burn and too lean to burn. So now lets take a 4 cylinder Lycoming. Why does it run rough? Because the cylinders are producing different amounts of HP compared to their neighbors. Where does this happen? It's not going to happen well on the rich side of peak where the power curve is flat, because a difference in fuel distribution is not going to give a big difference in HP. When we get near peak EGT and go on the lean side, the power curve drops off, so a small difference in fuel distribution will have a large effect on HP produced. So the most important question here is: Where does a correctly tuned carb engine run rough? And the answer is "somewhere near peak EGT or going into LOP operation."

If you got this information from his Basic Leaning class offered through the EAA, he was referring to fuel injected engines with balanced fuel injectors, although he didn't specify this. This method with a carb engine puts you right in the middle of the red fin, which leads to the highest ICPs (40-50 degrees ROP). The reason a carb engine runs rough is because you have gone past the power curve on the rich side of peak which is pretty shallow and are nearing peak EGT or even on the lean side a tad, where the power curve drops off dramatically and a small difference in fuel distribution between cylinders will be felt as roughness. Enriching to smoothness is going to either put you near peak EGT or best power, both which are unkind to the engine. I would encourage you to revisit this method. However, specifically for you, with running at 22 inches and 2300 RPM, I have you running about 63% power (my math might be wrong), which is right on the border of whether or not you are producing enough power to hurt anything at any setting. If this method is only used for this "low power cruise," well done! I just wanted to clarify that this shouldn't be done in just any cruise setting. On the other hand, if using this method with an injected engine, the advise is quite genius. What he is saying is to lean to the onset of roughness, which will take you through LOP and through best economy mixtures. The reason the engine will run rough now with balanced injectors is because the mixture is getting too lean to burn. Enriching it just enough will bring you back close to best economy, which is the whole idea of LOP (besides being kind to the engine.) Please understand my intentions with this post, as I am not trying to be "that guy on the forum" or criticize piloting technique, as in this case N5687Q is in good hands. I had the fortune of having a fellow (friends with Mike Busch in fact) as my CFI for a few years that understands this stuff at the molecular level. In no way am I an expert, I just hang out with them. And something about a Holiday Inn Express..... Hector-pilot report expected soon!!!

Yes, a carb engine can be ran LOP, usually with the aid of carb heat to help in atomization of the fuel. Depending on who you talk to, you will have different answers on the percentage of success. Mike Busch tends to think most carb engines can be run LOP if you really experiment with it. Some other people that have done it many times will give you around a 30% chance of success. The bottom line is this: 1.) It's OK to run ROP if you RUN RICH ENOUGH 2.) It's OK to run LOP, if you RUN LEAN ENOUGH Also, if you're at 60% power (some say 65%-I'm staying conservative) or below, you just aren't generating enough ICP (Internal Cylinder Pressure) to hurt anything, so keep the power low and you won't hurt anything experimenting with LOP. The worst thing that will happen to your engine is that it will say, "Nope, I can't run LOP. Sorry, I tried." Experiment with it. A great poll would be how many people with carb engines have one that can run LOP. Hector, since you operate at the higher altitudes, have you tried LOP?

Looks like some might have missed it. Apologies for the repost. Was going for a quick laugh.

Good points. For some of these topics, like how rich or lean to run, a graph can do wonders to provide a solution. Doesn't necessarily have to be winter time or the humidity to be high for carb ice to be likely. Remember at low power (when we're landing) the refrigeration effect is greatest. The choice is whether you want to loose about 10% power using carb heat or have the chance to loose 100% power when it ices up. The good news is that in the conditions that require carb heat usually are "better" than standard atmosphere so the performance of the airplane will be better than book. A consideration if hesitating to using carb heat because of the worry of the reduced power for a go around.

In the effort to offer breaking news, a local news channel called the NTSB to get the names of the pilots involved in the B777 crash at SFO. They talked to an intern without verifying his position within the organization. This is the actual broadcast: I understand lives were lost and this is not to take away from the losses suffered by others. Just an attempt to put a smile on people's faces.

Wow, that went off topic very quickly.

For mine, the actual cable broke. The fitting at the carb was fine. Makes me wonder the bending/torsional stress that's always on the cable and if it fatigues it over time regardless of how often it is used.

Is it possible to get a field approval/STC for a return spring?

Here's my control failure. Happened on the ground as well. I thought the carb had a return spring attached to pull the mixture to full rich if this happens. It doesn't. I consider these cables to be age limited. The TTAF was 2600.

Stefanovm is correct. Lean until roughness then enrichen two lines? This is fine for 60% power and below but I don't think this is the case. My avatar is the red fin graph. Learn it, live it, love it.