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?

nope..

but increasing mixture to pick up revs might not be the best idea.

Being electronic injection does it have knock sensors and variable timing?

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.

2 out of 3 posters so far know what I am about to say.

PM me :ok:

FCP
It has none of these. And knock sensors don't do to well on these engines ;)

If it has none of those things then whats the advantage (Other than weight?) of electronic ignition?

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.

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.

Ol' m8 just said it didn't have variable ignition timing in this case.

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?

Leaning a O-233
 

Sorry, I am using the Lightspeed Ignition.

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.

I would not want to be WOT at FL170 in one then :eek:

You sure about that? I am not saying never, but I have never seen such a thing or even heard of it.

Well, clearly it's unlikely you'd make it to FL170 before it began to misfire...

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.

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. :ok: