Try using some carb heat. It will smooth out that engine significantly when LOP. The warmer induction air does a much more uniform job of distributing the fuel as vapor with less liquid drop outs in the induction plumbing. -----Original Message----- From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of vtailjeff@aol.com Sent: Tuesday, October 15, 2013 8:21 AM To: lml@lancaironline.net Subject: [LML] Re: LOP ops on O-360 A1A Have you checked your baffling? Sent from my iPad On Oct 15, 2013, at 7:53 AM, Keith Smith <keith.smith@gmail.com> wrote: > Hey all, > > I'm waiting for winter to come around but it seems like my O-360 A1A has been running warmer than usual, requiring me to power back very shortly after takeoff to avoid an excursion north of 425 degree CHT's. > > In any case, I know that LOP ops are hard to come by with an O-360 due to poor fuel distribution. Indeed, my #4 cylinder peaks well before the others, making it tricky to get them LOP. > > I've been running in two modes...one is around 20 LOP to cool it down to around 385 CHT while the others run just slightly rich of peak. I can do this without much effort, and under a wide range of throttle positions, and density altitudes. > > On a recent flight, though, I found #1 and #3 settling on temps that were just too high to be happy with. I would go well ROP to get them cooled, but burned a lot of fuel in the process and still had a warm 4th cylinder due to the fact that it runs quite a bit leaner. This was all done at 75% power or less, btw, density altitude was well above 11k (I was at 11k and it was +10C) > > Eventually, I tried something somewhat dramatic. I was determined to get ALL the cylinders LOP. I leaned relatively rapidly and ignored the disconcerting knocking/shuddering associated with the uneven amounts of power being produced between the 4th cylinder and all the rest. > > It all happened a bit quickly, but with cylinder 1-3 roughly 20-40 LOP and #4 70-90 LOP, the CHTs dropped like a stone, seemingly in seconds, down to 380-385 across the board for #1-3 with #4 now in the 350-360 range. With careful fiddling of the mixture, and countless experiments with throttle position, I got the vibration down to the point where it was barely noticeable. Eventually it just felt smooth...but I can't tell if I got used to it, or things just settled down, although I wouldn't think it was possible. > > Final fuel flow was around 8.8-9.0 gph. > > Finally, living the LOP dream with my O-360 :) > > I tried repeating this later on, down low and wasn't able to repeat it (ie, never got it smooth). > > So, it's elusive, but possibly doable under just the right circumstances. Since I do long trips on a regular basis, I'm definitely interested in making this work. > > Separately, I'll try to find out why it's running warmer in general. I did have a mag replaced, the other rebuilt, and 4 new plugs installed in the last year. > > Honestly, I'm going to try to save some clams and get this converted to an IO-360 (didn't realize it was relatively inexpensive until my mechanic suggested it), get balanced injectors and run LOP as SOP. The difference in cooling really is staggering. I know I'm probably preaching to the choir, but I thought that O-360 owners might find it eye opening. Get up high and give it a try if you have a 4 point engine monitor. You'll know it's working when your leaning results in EGT and CHT's coming down :) > > The trip, btw, was N07-KFTW-KSAV-N07, around 2600nm. > > Keith -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html