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Here is how I have done it.
Apx 3-4 seconds of prime after the fuel pressure gauge hits 20#----with the mixture at full.
Crack throttle, crank----usually starts 2 or3 blades. I always use the bypass valve to shut down the engine, never touch the mixture for shutting down. Find out what works for you, and stay with it. |
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FM200?
If you really have 6gpm flow at 1000rpm your idle mixture is way too rich and needs to be adjusted. If so, it is no wonder you have an erratic idle. Refer to the very nice instruction book from Airflow Performance on how to adjust. Using the mixture rather than the purge valve during start and shutdown will leak raw fuel into the throttle body causing a couple problems. Check with Don at Airflow and he will probably tell you those things first. He can also sell you an instruction manual.
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Fuel flow indications at idle can be quite un-reliable in my experience.
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But Happy to learn something new. Please tell me more about the setup you believe is optimum. Of the ones I have seen, setup and tested as per the instructions, they all have been responding to ground leaning as I expected. Not sure how much measrured effect it has on WOT/FR from the idle circuit. Never been interested to test it but it would be insignificant I would have thought. |
Mattituck Engines website
To the thread starter, my own experience is most similar to RV 10 in Oz.
Check the tech advice section of Mattituck Engines website, then click on "Good operating habits" On the ground my mixture lever is about half way to ICO for peak rpm. Best of luck! PS I never purge, hot or cold. 2 slick mags,Slick Start on LH side. Air Flow Performace FI I would guess you are flooding the pre start and running too rich after started. On the ground at idle you can not hurt anything By leaning for peak RPM. |
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Conversly most of the FI engines I see seem to run cleaner plugs overall and generally have less lead deposits even with no ground leaning (myself included). You can adjust both for a 50 RPM increase, but in both cases the above still holds true. I think the off idle mixture may be better controlled in the FI system and/or better atomization of the fuel may also be a factor. |
:DAgreed, and the reason for better atomisation in the FI is most likely the air velocity and temperature of the engine early on, the cold one is not going to atomise as well with the carby.
I would suggest that following my tips in the previous posts will minimise lead balls, over 50 hours we get very few if any. Like I say, does everything it should and nothing it shouldn't. One other benefit is that done the way I describe there is no chance whatsoever of anyone taking off partially leaned and in detonation. It drives me mad when I see folk lean just a little bit. One day they will forget and not realise it. Will clean up the pistons and heads nicely though! |
I'll start with mixture adjustment
Thanks for all expressed wisdom here!
AFP's recommended procedure without purge valve is: Mixture ICO Throttle 1/8 Boost On Move Mixture to full rich until FF 4-6gph and return to ICO Boost off Crank. When engine fires move Mixture to full rich and throttle to idle. This is what I've tried - without success. The high fuel flow is surely a sign that idle mixture is too rich. I had my difficulties to properly adjust mixture and idle rpm. The main problem was that an adjustment that was OK one day was off the next day. When Idle was adjusted to 750 rpm on day one it got below 600 rpm the next day. The same with the mixture. It was very sensitive to adjustments. When checking the mixture my DAR stated it was too lean, as there was no rpm rise when putting the mixture to ICO. I then adjusted the idle mixture by turning the rod one flat and that's I have been using. RV10inOz: Your cold star procedure puzzles me: You crank with mixture ICO. When it fires, I suppose you run the mixture up as you describe in "hot start"? So the first thing I will look at is idle mixture and see if aggressive leaning can make the engine smoother on ground. |
I think we are homing in on the problem.
Your question to OZ tells me that you are cranking with the mixture full rich, yet a few lines above you correctly describe the cold start procedure as stated by AFP. 4th line from the top Quote:
Your right hand will be on the power Knob (mixture:)) when the engine fires, advance the mixture knob. You are correct, the adjustments to the idle mixture is very sensitive and unless you accomplish this task with an engine at operating temperature as described in the AFP manual you'll be chasing that sweet spot, where you get a 50 RPM rise on shut down forever. As to leaning the mixture to the max with fuel injected engines I can't argue with Walt's real life experiences when looking at engines at overhaul time. However, the 50 RPM rise you get on shut down is added richness you don't need for taxiing around and at today's fuel prices you might as well lean it to the max, you can't hurt the engine by leaning it on the ground. While fouling the plugs is indeed a problem of less concern in injected engines, leaning to the max on the ground especially on the way back to the hangar will keep the plugs cleaner and ready for an easy start next time you go flying. |
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