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genie(at)swissmail.org
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 Posted: Sun Sep 28, 2014 1:54 am Post subject: O-320 Sputtering on One Magneto |
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Yesterday I test ran my O-320. When taking it up to 1800 rpm it
sputtered on one magneto but ran well on the other.
Thereupon I set the engine to 1000 rpm and ran on the magneto which
caused sputtering. I slowly raised the speed to 1800 rpm and the engine
ran well. I tried the other magneto and then both and it continued to
run well. There was little difference in speed between one magneto and
another, and the difference with one magneto and both was about 150 rpm.
Thereupon I shut the engine down.
After that someone reminded me about the method of running the engine
and leaning out to remove deposits and prevent sputtering. After almost
half an hour I restarted the engine, ran up to 1800 rpm on both magnetos
and gently leaned out until the engine started to run erratically. I
then tested the magnetos with rich mixture and the drop was within
around 150 rpm with little difference between each magneto.
Does anyone know which is the better method of the two to clear spark
plugs, or whether there is a still better method? Thank you.
When switching off both magnetos for a moment while the engine was
running at around 1000 rpm I got a bang. Is that because of backfiring
or dieseling? Is such a procedure recommended? I know that one gets
backfiring if one switches off the engine with the magnetos and not by
leaning out.
George Nielsen
RV-6 PH-XGN
The Hague, the Netherlands
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stuart(at)stuarthutchison
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| Posted: Sun Sep 28, 2014 4:50 am Post subject: O-320 Sputtering on One Magneto |
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G’day George,
A common problem. As distinct from in-flight leaning (which can have serious consequences if not properly managed), on the ground you can pull the idle power mixture way back (straight after start) until the engine just about stops then richen slightly. There isn’t enough fuel to lead foul the plugs, nor enough fuel to cause high EGTs, so you really can’t hurt the engine on the ground by leaning that far with very low power/load. If you attempt to takeoff with the mixture that lean, then the engine simply doesn’t have enough fuel to respond and it’s plainly obvious! Conversely, doing this by halves may leave you short of power on takeoff if you forget to select full rich, so do this very positively or not at all.
If you do get plug fouling, method 2 - running the engine up to 1800-2000 rpm slightly leaned with BOTH magnetos selected (to burn all the fuel and generate heat in the cylinder) is the preferred way here in Australia.
The bang is normal and like any backfire … momentarily turn the spark off while the fuel / air is still flowing and you can cause an explosion in the exhaust pipes (i.e. outside the cylinders) when the spark is re-energised. Yes, you should do this quickly before shutdown to ensure neither of the magnetos are live with the ignition switch off. The longer you leave the magnetos off the more chance you have of a backfire …. this need only be very momentary. Remember that the magnetos are self-sustaining after start and that the ignition switch is designed to ‘ground’ the magneto to stop the spark … so if either of the P-leads are broken, the switch is unable to ground the magneto and the engine would remain live even with the switch in the off position.
Cheers, Stu
On 28 Sep 2014, at 7:52 pm, George Nielsen <genie(at)swissmail.org> wrote:
| Quote: |
Yesterday I test ran my O-320. When taking it up to 1800 rpm it sputtered on one magneto but ran well on the other.
Thereupon I set the engine to 1000 rpm and ran on the magneto which caused sputtering. I slowly raised the speed to 1800 rpm and the engine ran well. I tried the other magneto and then both and it continued to run well. There was little difference in speed between one magneto and another, and the difference with one magneto and both was about 150 rpm. Thereupon I shut the engine down.
After that someone reminded me about the method of running the engine and leaning out to remove deposits and prevent sputtering. After almost half an hour I restarted the engine, ran up to 1800 rpm on both magnetos and gently leaned out until the engine started to run erratically. I then tested the magnetos with rich mixture and the drop was within around 150 rpm with little difference between each magneto.
Does anyone know which is the better method of the two to clear spark plugs, or whether there is a still better method? Thank you.
When switching off both magnetos for a moment while the engine was running at around 1000 rpm I got a bang. Is that because of backfiring or dieseling? Is such a procedure recommended? I know that one gets backfiring if one switches off the engine with the magnetos and not by leaning out.
George Nielsen
RV-6 PH-XGN
The Hague, the Netherlands
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BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
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| Posted: Sun Sep 28, 2014 7:00 pm Post subject: O-320 Sputtering on One Magneto |
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George:
The procedure to do a Mag Check is:
~1800 RPM
~Left Mag - observe RPM
~Both - observe RPM
~Right Mag - observe RPM
Now, I also do a Mag check at 1500 RPM. Why? Because as RPM increases so does the output of the Mag. So, at a lower RPM if there is a problem you should easily find it.
Neither of your two written Plug Clearing Procedures are correct. The procedure to clear fouled plugs is:
~HOLD YOUR BREAKS - DO NOT USE THE PARKING BRAKE - HOLD YOUR BRAKES... Long story - It is a safety reason.
~Slowly [Don't go ridiculously slow.] increase the RPM to MAX STATIC RPM. Around 2200 to 2300 RPM.
~ LEAN - Lean until rough and richen just a little, VERY LITTLE.
~Hold the RPM and Lean for about 20 seconds
~Slowly decrease the RPM back to 1000 RPM. Let it run here for 1 minute.
~Then do a Mag Check (see above). If you still have a fouled plug REPEAT the procedure for fouled plugs. Repeat three (3) times if necessary. If you have done the procedure correctly for the three (3) times and still have fouled plugs - - - Remove and Inspect the Plugs.
Barry
"Chop'd Liver"
On Sun, Sep 28, 2014 at 5:52 AM, George Nielsen <genie(at)swissmail.org (genie(at)swissmail.org)> wrote:
[quote]--> LycomingEngines-List message posted by: George Nielsen <genie(at)swissmail.org (genie(at)swissmail.org)>
Yesterday I test ran my O-320. When taking it up to 1800 rpm it sputtered on one magneto but ran well on the other.
Thereupon I set the engine to 1000 rpm and ran on the magneto which caused sputtering. I slowly raised the speed to 1800 rpm and the engine ran well. I tried the other magneto and then both and it continued to run well. There was little difference in speed between one magneto and another, and the difference with one magneto and both was about 150 rpm. Thereupon I shut the engine down.
After that someone reminded me about the method of running the engine and leaning out to remove deposits and prevent sputtering. After almost half an hour I restarted the engine, ran up to 1800 rpm on both magnetos and gently leaned out until the engine started to run erratically. I then tested the magnetos with rich mixture and the drop was within around 150 rpm with little difference between each magneto.
Does anyone know which is the better method of the two to clear spark plugs, or whether there is a still better method? Thank you.
When switching off both magnetos for a moment while the engine was running at around 1000 rpm I got a bang. Is that because of backfiring or dieseling? Is such a procedure recommended? I know that one gets backfiring if one switches off the engine with the magnetos and not by leaning out.
George Nielsen
RV-6 PH-XGN
The Hague, the Netherlands
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