View Full Version : 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?
Ultralights
15th Sep 2015, 07:46
nope..
but increasing mixture to pick up revs might not be the best idea.
FoolCorsePich
15th Sep 2015, 08:23
Being electronic injection does it have knock sensors and variable timing?
Aussie Bob
15th Sep 2015, 08:51
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.
Jabawocky
15th Sep 2015, 13:32
2 out of 3 posters so far know what I am about to say.
PM me :ok:
Jabawocky
15th Sep 2015, 23:06
FCP
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 ;)
FoolCorsePich
15th Sep 2015, 23:14
If it has none of those things then whats the advantage (Other than weight?) of electronic ignition?
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.
Andy_RR
16th Sep 2015, 02:54
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.
FoolCorsePich
16th Sep 2015, 03:30
as well as speed and load-dependent advance.
Ol' m8 just said it didn't have variable ignition timing in this case.
Jabawocky
16th Sep 2015, 05:48
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?
Sorry, I am using the Lightspeed Ignition.
RadioSaigon
17th Sep 2015, 05:54
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.
Jabawocky
17th Sep 2015, 07:23
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.
Andy_RR
17th Sep 2015, 10:44
I would not want to be WOT at FL170 in one then :eek:
Well, clearly it's unlikely you'd make it to FL170 before it began to misfire...
RadioSaigon
17th Sep 2015, 11:09
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.
Jabawocky
17th Sep 2015, 12:56
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: