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Leaning a 233

Old 15th Sep 2015, 07:57
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Lsa
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Leaning a 233

The book says to lean a O-233 Lycoming to max revs at a particular throttle setting. I have tried leaving it at WOT and controlling cruise revs with mixture.
EGTs around 1300, with lower CHTs. Engine runs smooth and has dual electronic ignition. Anyone see a problem with this?
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Old 15th Sep 2015, 08:46
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nope..

but increasing mixture to pick up revs might not be the best idea.
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Old 15th Sep 2015, 09:23
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Being electronic injection does it have knock sensors and variable timing?
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Old 15th Sep 2015, 09:51
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Do you have an engine monitor? I do and I find with my engine (O360) that having the throttle cracked back a bit from wide open results in a much better distribution of fuel to all cylinders. A whisker of carby heat sometimes helps this too.
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Old 15th Sep 2015, 14:32
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2 out of 3 posters so far know what I am about to say.

PM me
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Old 16th Sep 2015, 00:06
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Being electronic injection does it have knock sensors and variable timing?
It has none of these. And knock sensors don't do to well on these engines
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Old 16th Sep 2015, 00:14
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If it has none of those things then whats the advantage (Other than weight?) of electronic ignition?
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Old 16th Sep 2015, 03:30
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Lsa
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Leaning a O-233

The main advantage is it has a much higher energy spark that can only be utilized by using automotive plugs. Timing is also variable via MAP.
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Old 16th Sep 2015, 03:54
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electronic ignition also is much more repeatable over the long term compared with (traditional) mags and allows optimizing ignition for starting as well as speed and load-dependent advance.
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Old 16th Sep 2015, 04:30
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as well as speed and load-dependent advance.
Ol' m8 just said it didn't have variable ignition timing in this case.
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Old 16th Sep 2015, 06:48
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LSA

Is the Lycoming O-233 actually using a MAP derived spark timing controller? I did not think they were? Or have you added one?
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Old 16th Sep 2015, 07:39
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Lsa
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Leaning a O-233

Sorry, I am using the Lightspeed Ignition.
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Old 17th Sep 2015, 06:54
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Not certain about the 233, but some (many?) old Lycosauruses and Conti's had a non-selectable full-rich mixture at wide-open throttle. It was always necessary with those engines to back the throttle off a ways before attempting any leaning.
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Old 17th Sep 2015, 08:23
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I would not want to be WOT at FL170 in one then

You sure about that? I am not saying never, but I have never seen such a thing or even heard of it.
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Old 17th Sep 2015, 11:44
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Originally Posted by Jabawocky View Post
I would not want to be WOT at FL170 in one then
Well, clearly it's unlikely you'd make it to FL170 before it began to misfire...
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Old 17th Sep 2015, 12:09
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Originally Posted by Jabawocky
You sure about that? I am not saying never, but I have never seen such a thing or even heard of it...
Don't take my word for it -it's a pretty well-documented fact. A Google search should throw it up... from memory, I think Mike Busch wrote an article on it, but it's been a long time since I could muster the enthusiasm to look ;-)
In my experience, usually only on fixed-pitch aircraft. Pick a 172, any one will do, keep an eye on the EGT and you'll see it for yourself.
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Old 17th Sep 2015, 13:56
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RS

I reckon you are thinking about the enrichment circuit that givens a higher flow when at full throttle. Back it off a fraction and that circuit is closed.

That exists, but you can still lean the mixture at WOT.
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