garytex

Cool. I'm really ready to start flying. I have to go AUS - Fort Stocton - Del Rio for work, then we are working cattle on Fri so on to Falfurrias - AUS , and am going to have to do it in my Cheetah, as 9504M isn't ready yet. I could almost cry.

I visualize it very much like reloading low expansion ratio (bottleneck case) versus high expansion ratio (straight wall case) ammunition. The burn speed of the powder must match the expansion ratio, the bullet is running away from the combustion chamber, you really do not want detonation, and the longer you can keep the burn progressive, the faster the bullet goes. In my engine I try to increase the burn rate by increasing pressure (MP or altitude), running closer to stoichometry, slowing the prop, or with this weird timing issue, advancing the spark. The reverse reduces burn rate and pressure. LOP is another way to decrease pressure, with the added benefit of reducing the molecules of hydrocarbon out on the dance floor. Every one of them gets to danceWe can substitute our higher compression ratios and earlier spark for gas and still keep the flame front moving along quickly enough to push the piston. And slowing down airspeeds just a little bit generates geometrically larger reductions in the thrust demanded by our airframes. Even less gas It's all good good good. I still have a lot to learn about LOP, but finally have a group of like minded folks to bounce ideas off, and a much better theoretical framework assembled in this forum within which to experiment and ponder, for which I am grateful. I previously only flew fixed props, and carburetor equipped (poor mixture distribution) engines, and am excited about the new number of variables to play with in my new F. The down side is that my wife hates it when I adjust the mixture and the engine stumbles, and thinks that all that fooling around can't be good. "Please leave all the controls alone. Quit touching everything. You're like a damn raccoon. Quit fiddling with all the knobs and staring off into the distance. Please, you're making me nervous." Good arguments for the one big pull technique, I guess.

Unless my understanding of several interacting processes is wrong (which makes error almost a certainty) it works something like this. We know that lower cylinder pressures slow the progression of the flame front. Leaner mixtures also slow the flame front. As soon as the piston starts down, pressures fall even faster, and the burn shifts from progressive (the faster it burns the more pressure it makes, the more pressure its under the faster it burns), to regressive. The other variable is ignition timing, which may be set for either 20 or 25 degrees before top dead center. See the timing thread in Vintage. So lower manifold pressures, leaner mixtures, and later timing all slow the burn, meanwhile the piston is busily "running away" from the combustion, also lowering pressures. Thats why peak is sometimes the way to go at altitude for any except the most evenly mixture distributed engines. Thats also why it is easier to run LOP down low. I think this is what is going on, the mystical piece of it can be explained by understanding that too lean doesn't just mean that the mixture can't burn. It also means that the mixture slows down in a fast moving environment and that can be another source of inefficiencies. Lots of speculation here, anybody else see it that way? Gary

Your last runway incursion incident involved a javelina darting across a friends driveway.

Thank you for the input. I have been waiting with baited breath to get my hands on my just purchased F model. It is at Dugosh getting a new oil cooler, the $300 square accordion intake fitting, and a flap jack shaft bell-crank attach point crack fixed. (if you got the flap jack shaft, does that mean the lady at IHOP brought you no pancakes?) I'll have them check the timing (I'm still afraid of the buzzer and flashing lights) and hopefully not forget to unfold the feet after I'm done with my complex checkout. This is a great forum and a wonderful information source, a reflection of the members. Thanks again, Gary

Thanks for the answers. I'll have my mechanic set mine at 25 BTDC if it isn't already. (I am still scared of the buzzer and flashing lights) Sincerely, Gary

I noticed that Jetdriven mentioned that he had his timing changed from 20 deg. BTDC to 25 deg. with better performance noted, especially LOP. The below info from the type certificate for the I0-360 A1A ends with the note that 25 deg. is spec, with 20 deg optional. Pretty weird, huh? So, how is your timing set, why, and what effect do you see? Anyone else changed timing and has before and after? 1E10 Page 2 of 18 Model (cont'd) IO-360-A1A, -A1B, -A1B6, -A1B6D, -A1C, -A1D, -A1D6, -A1D6D, -A2A, -A2B, -A2C, -A3B6,-A3B6D, -A3D6D, -C1A, -C1B, -C1C, -C1C6, -C1D6, -C1E6, -C1E6D, -C1F, -C1G6, -D1A, -J1AD, -J1A6D, -K2A LIO-360-C1E6 AIO-360-A1A, -A2A, -A1B, -B1B AEIO-360-A1A, -A1B, -A1B6, -A1C, -A1E, -A1E6, -A1D, -A2A, -A2B, -A2C IO-360-B1A, -B1B, -B1D, -B1E, -B1F, -B1F6, -B2E, -B2F, -B2F6, -B1G6, -B4A, -E1A, -F1A, -M1A+ AEIO-360-B1B, -B1D, -B1F, -B2F, -B4A, -B1F6, -B2F6, -B1G6, Oil, Lubrication (Lubricants should conform to the specification as listed or to subsequent revisions thereto) Lycoming Spec. No. 301 and Service Instruction 1014 - - Temperature NOTE 1 - - Pressure NOTE 2 - - Sump capacity, qt. 8 - - (Except AIO series) AIO series - Dry Sump ? Usable oil qt, (Except AEIO series) 6 - - Engine Position NOTE 14 - - Usable oil qt., (AEIO series) 4 - - Ignition, dual Magnetos NOTE 7 - - Timing °BTC 25* 25 Spark plugs NOTE 4 - - Bore and stroke, in. 5.125 x 4.375 - - Displacement, cu. in. 361 - - Compression Ratio 8.7:1 8.5:1 Turbocharger NOTE 9 - - Weight (dry) lb. NOTE 7 - - C.G. Location (dry with starter and generator installed) NOTE 7 - - Propeller shaft, SAE No. AS-127 Flange, Type 2 Modified - - Crankshaft Dampers and Balancers NOTE 12 - - NOTES 1,2,3,4,5,7,8,9,10,11,12,16 1,2,3,4,5,7,10,11,12,16 "- -" indicates "same as preceding models" "?" indicates "does not apply" + IO-360-M1A has an alternate rating of 160 BHP at 2400RPM * All models except IO-360-A1B6D and -A3B6D have optional timing of 20°BTC

As a newb, I've been reading the operators manual for the Lycoming 0 and IO 360 family, it says to warm up with cowl flaps open, 1000 - 1400 RPM, Prop in fine pitch, full rich, (which advise I'm going to ignore) for the above stated reason, hot spots. Happy thanksgiving, Gary

Yes, that looks like just what the baffle leprechaun ordered. Thanks so much, Gary

I do not know about the J, but that would be another example, and we know that is a successful engine installation. Maybe someone with a J will wander over into Vintage, looking for used jeans or a vinyl and chrome chair, and illuminate things for us. Either that or we will have to get off our behinds and physically go look at one, blogven forbid.

Ron Thanks for the picture. What you show is what I expected to see and didn't. The missing pieces are the bottom wrap from the front of the front cyl. and the safety wire running back and holding it and the back wrap comming forward, and holding both tight against the bottom and redpective sides of the cyls. We may need a visit from the mooney baffle leprechaun. Thanks, Gary

First off let me say that I think you have a wonderful forum here. Second, I am thrilled to now finaly have a Mooney. It only took 20 years and two other airplanes. My question. My SWTA cowl seems shy in the provision of baffles to wrap the bottom of the cylinders, particularly the front half of the front cylinders. I called Rus, and no, thats all they certified it with. I was wondering what experience others might have had with that or the MAC cowl cylinder baffling. Thanks, Gary

I remember reading in the Lycoming Operators Manual, 60297-12 for the O-360 family that the minimum oil operating quantity is 2 quarts. The oil filter on my Cheetah was a sob to get off, and every other oil change was just that, an oil change. I would drain the oil, pour in 3 quarts, run it at about 1000 rpm for a few minutes, drain that, put in 6 and fly away. I suspect that I will not be comfortable not opening the filter and looking for pieces large enough to have part numbers on them in the screen on my just purchased F for the first few oil changes, as I am not familiar with the engine yet, but I'll get there. Gary