ccsmith51
Well Known Member
I have an O-360-A1F6D on my RV-4. Yesterday when I did my 1700 RPM run up it was VERY rough on the right mag (Bendix dual mag), for a number of attempts. Left mag was fine. I ran it up to 2000 RPM for a moment, and then all was fine. I flew for 0.7 hours and tried both mags at different RPM's (2000 - 2700) and altitudes (1500 - 4500) and didn't have a drop of more than 75 RPM. Flight before was six days earlier, with no problems.
It was a bit chilly (for FL), about 55°. The engine took about 8 seconds of cranking to catch (accelerator pump carb, no primer system). When it caught it ran fine. I leaned once it was started.
Last summer on my trip west I was having a right mag issue with what I would call "backfiring" on run up. I was told that it was not backfiring, but in fact a plug that wasn't always firing and and fuel was igniting in the exhaust pipe. We checked the plugs and replaced the right rear lower plug, and that cured that problem. That was about 20 hours ago.
About three hours ago I replaced all eight spark plugs with new RHM40E's. I have had no issues until yesterday. I can't believe that with only three hours on the plugs, and leaning when taxiing, I could have lead fouling, but I don't know...
My last condition inspection was 3/12, and since the engine logs are incomplete, and since it is a single case dual mag, I decided to have it overhauled. The shop said it looked like the mag had very little time on it. So, it was overhauled (new points and bushings, condensers were fine) and yellow tagged 9 months ago.
I'm trying to give as much background as possible, so when I ask the question y'all will know what I know...
What could cause a very rough mag under the circumstances above?
Thanks,
It was a bit chilly (for FL), about 55°. The engine took about 8 seconds of cranking to catch (accelerator pump carb, no primer system). When it caught it ran fine. I leaned once it was started.
Last summer on my trip west I was having a right mag issue with what I would call "backfiring" on run up. I was told that it was not backfiring, but in fact a plug that wasn't always firing and and fuel was igniting in the exhaust pipe. We checked the plugs and replaced the right rear lower plug, and that cured that problem. That was about 20 hours ago.
About three hours ago I replaced all eight spark plugs with new RHM40E's. I have had no issues until yesterday. I can't believe that with only three hours on the plugs, and leaning when taxiing, I could have lead fouling, but I don't know...
My last condition inspection was 3/12, and since the engine logs are incomplete, and since it is a single case dual mag, I decided to have it overhauled. The shop said it looked like the mag had very little time on it. So, it was overhauled (new points and bushings, condensers were fine) and yellow tagged 9 months ago.
I'm trying to give as much background as possible, so when I ask the question y'all will know what I know...
What could cause a very rough mag under the circumstances above?
Thanks,
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