DXB Posted October 1, 2019 Report Share Posted October 1, 2019 I think it was @cliffy who provided a lucid discussion here a while back on why the enrichment circuit that gives extra fuel at takeoff makes essentially no contribution when WOT at altitude, but I have forgotten the details. I have tried the tricks of cocking the throttle plate slightly and / or adding a little carb heat in order to get a better mixture distribution and lean a little more (a true CB at heart). But I sadly haven't seen any benefit in my hands. Mine consistently starts running rough at between 10-20 degrees lean of peak on the leanest cylinder. It sounds like others have better luck. But when @Hank talks about running his Lycoming O-360 at -25 lean of peak, I'd be willing to wager he is just talking about LOP on the single cylinder he is monitoring, and the rest remain at peak or ROP. In aggregate, this is still a ROP situation, which I think is an insurmountable limitation of the O-360. I would add that, unlike the lean find feature on my EDM900, the fuel flow is an incredibly useful tool. The fuel flow at which I gets roughness when leaning seems quite consistent at a given power setting, so I rarely bother to pull it back to roughness anymore. I just set the fuel flow I want with the mixture knob and go. Doing so may reduce the hassle factor some for @bluehighwayflyer 2 Quote Link to comment Share on other sites More sharing options...
Andy95W Posted October 1, 2019 Report Share Posted October 1, 2019 27 minutes ago, bluehighwayflyer said: Yes, as soon as I have time I am going to install an EDM 900 and a vernier mixture control and get rid of all of the original OEM engine instruments, which is all I currently have. Well except for an analog 4 probe Alcor EGT instrument. I don’t have fuel flow. I added a FS450 to my previous J for fuel flow so I could set power LOP more efficiently and I just loved it. I have been tempted to put one in the C, primarily because it is a much less-involved installation than the EDM 900, but I’m holding out for the more “permanent” solution. On the other hand the C has been flying on the OEM engine instruments without incident for 54 years now. Sometimes I wonder if we really “need” all of these new fangled gadgets as much as we think we do. Jim I feel the same way as Jim, but that is why I chose the JPI 730. I actually like the old MP/FP and tach gauges, and I don't have a problem with the OEM gauges, I just wanted them to be more accurate. On the plus side, if the JPI goes dead, I'm still legal to fly, and if one of my OEM gauges goes wonky (like oil pressure/temp), I'm still safe to continue to my destination. Quote Link to comment Share on other sites More sharing options...
Andy95W Posted October 1, 2019 Report Share Posted October 1, 2019 I'll admit it, I'm weird! I swapped out a modern MP/FP gauge for the old style, because I like the old Mooney bird. I even put one on my tail: 1 Quote Link to comment Share on other sites More sharing options...
DXB Posted October 1, 2019 Report Share Posted October 1, 2019 44 minutes ago, Andy95W said: I'll admit it, I'm weird! I swapped out a modern MP/FP gauge for the old style, because I like the old Mooney bird. I even put one on my tail: I really like the towel bar NAV antenna conversion. Was that hard to do? Quote Link to comment Share on other sites More sharing options...
Andy95W Posted October 1, 2019 Report Share Posted October 1, 2019 1 hour ago, DXB said: I really like the towel bar NAV antenna conversion. Was that hard to do? No, it was easy. A previous owner did it back in 1997. Them things are expensive! 1 Quote Link to comment Share on other sites More sharing options...
RobertGary1 Posted October 1, 2019 Report Share Posted October 1, 2019 Absolute EGT numbers are worthless, its more an indication of how the probes were installed. But relative numbers are interesting. You can raise and lower your EGTs a lot just by moving them up or down your exhaust pipe. What did the A&P who installed them have for lunch that day? -Robert Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 2, 2019 Report Share Posted October 2, 2019 be nice to the raw data... Absolute EGT numbers have worth... But they don’t have as much value as the peak, or ROP/LOP numbers... For those operating a turbo... TIT is a similar number... it is a raw data point that when used properly keeps the metal from melting away... If you see an unusual raw peak EGT number... it suddenly has a lot of value.... or worth? Calibrating them with their known locations to what they mean is a bit challenging... but if you have a set of data that always works, and then something changes... it becomes more valuable... Something to keep in mind when people say the raw EGTs have no value... they do sort of... to some people... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
rbridges Posted October 2, 2019 Report Share Posted October 2, 2019 I go by CHT. I adjust my mixture to stay at 360 or less. I also keep an eye on oil temp; alarm is set for 210. I do watch egt, but it usually falls in line when cht is in check. Any issues doing it this way? Quote Link to comment Share on other sites More sharing options...
Cruiser Posted October 2, 2019 Report Share Posted October 2, 2019 my peak EGT numbers are in the mid 1500s my #3 goes as high as 1565°F I usually run 40 - 50 LOP with the highest EGT just over 1500 and the rest in the high 1400s CHT are all below 350° F Quote Link to comment Share on other sites More sharing options...
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