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12-15-2003, 11:02 PM | #1 |
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How cold is too cold for ABC break-in?
I posted this on RCU...then I thought to myself...what the heck do they know about cold?
I've got shiny new MVVS .91 on the front of my Extra. Today I received a beautiful Pitts exhaust from Bisson Custom Mufflers, so I bolted it all up, and am dying to make some noise with it. The temperature in my neck of the woods hovers around freezing (0 degrees celsius give or take a couple, 32ish to you 'muricans ). I've always strapped a plane with a new engine to a picnic table and run 2-3 tanks before flying. Any thoughts about breaking in a new engine when it's a little brisk out? I've got some 5% nitro Omega (pink), and was planning to add a couple extra ounces of castor to the first gallon as a precaution. Thanks for your time. |
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12-15-2003, 11:24 PM | #2 |
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I am: Steve H.
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Great question, wish I had more experience to draw from directly related to the topic. Never started a new engine in the winter. I know most would say light it up and don't worry about it, probably the case but, myself I think I would wrap the cylinder in tin foil and preheat the engine with my heat gun, start it up and follow a normal break in using the main needle. I would not allow it to cool as much between tanks though.
Pre heating it before turning it over should make it safe, tin foil should help keep the heat in. Andrew should have good advice? |
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12-16-2003, 11:36 AM | #3 |
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The engine will run fine. I break in engines every year outside during the winter.
Just make sure, as soon as it starts to open the carb FULLY and set the needle for a slightly rich run. You want the engine to come up to working temps (which it will) but just dont leave it at idle, or even half. Open the carb and set the top end to run noticeably off peak, but not slobering. It should be running without the glow plug heat on. I havent ever had the need to preheat and engine, and have only heard of guys doing that when it is really cold (like way below 0 degrees C)
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12-23-2003, 09:11 PM | #4 |
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Thanks Andrew. I decided that because I've never flown off snow, it may be a good idea to try it out with the trainer first. I put a new MVVS 49 on it and fired it up. Even at -2C, it was running like a charm after one 8 oz tank of fuel. Did it pretty much as you suggested and it seems to be a happy engine! If thei snow flying thing isn't too traumatic, maybey I'll spark up the Extra too!
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12-23-2003, 10:40 PM | #5 |
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Hey great, be sure and let us know how it does David. I'm gettin the ski's out to put back on my CG Extra. I haven't really run up the plane this summer due to some glitches i had with the electronics earlier in the year. Hopefully the engine will run up fine and I can fly off the lake(ice) soon. If I do, I'll be sure to take some pics and post em.
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12-24-2003, 08:43 AM | #6 |
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Cold Engines
We fly in the winter all the time (since its here for half the year ) and engines seem to start fine right down to 20 below c (=friggin cold!). I find that if the engine is not left out in the breeze between flights, it stays warm enough to fire up for the requesite 3 flights, and they run like stink with the highdensity air! In fact you will want to richen up the carb slightly so you don't throw a rod or some other horrible.
Now trim changes and plastic covering shattering are another thing Happy Holidays everyone |
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12-24-2003, 12:17 PM | #7 |
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Lee, I am a wus - when it is -20 I can think of many better things to do than have my bare hands behind a prop with 100+ mph winds coming off the backside.... and then you spill fuel on your hands.... doh!
Warm and indoors, thinking of flying while I am building. Thats my winter.. I do run engines outside on the test stand, but I can wear gloves for that!
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12-24-2003, 12:40 PM | #8 | |
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01-02-2004, 07:45 AM | #9 |
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An ABC engine should be broken in at it's operating temperature and rpm on a rich needle setting just into the two stroke, using the fuel you intend to use during it's life. It is not possible to achieve this with the propelor that would normaly be used for flying, it is too large. Reduce the diameter of the prop to allow the engine to turn up to it's rpm and temp. with the rich setting. On a .91 size prop I would guess up to 4" could be taken off the diameter.
The heat gun treatment is not to make the engine easier to start in cold weather. The very worst thing one can do to an ABC engine is to turn it over when cold, especially when new. On a new ABC engine Use the heat gun to expand the top end so that the piston is not being jammed up into the liner at TDC and dragged out again as the engine turns over. Improper break in of an ABC engine can ruin it as far as top performance is concerned before it even gets into an airplane. Ed S |
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