Anticept Posted May 25, 2017 Report Share Posted May 25, 2017 Spent a LOT of time on this one. Mag drop 200 / 350. Occasional miss. First time working with this airplane. Replaced plugs (gave them back to owner saying they look fine, and to hang onto them just in case), replaced boots (they were falling apart anyways, being 11 years old), pulled apart the carbs and cleaned them out, tested coils, tested trigger coils, tested with a different set of ignition modules that I have spare, switched ignition module to coil connections and the problem jumped sides, and was about to replace the coil pack, when I sat back and thought about all the tests I had done so far. I remember it ran better in the cold than the heat... and got a clue. Might have finally resolved it. Took the carbs back out again and pulled the needles out. Saw this: Those clips are in the wrong place, they should be in position 3; they were in position 2, resulting in a leaner mix. After switching them to position 3 and reassembling, the mag drop problem went away, with a 10 RPM spread, around 150 drop. Maybe a whole bunch of factors came out just right that one of the plugs couldn't get a good burn started in time because of the leaner mix, occasionally missing. That's the only explanation I have that fits all the test results that I had, including switching those connectors. Link to comment Share on other sites More sharing options...
Tom Baker Posted May 25, 2017 Report Share Posted May 25, 2017 I had the same exact problem with one this past summer after doing a hose change. It is frustrating, because you looking for an ignition problem when it isn't an ignition problem. Link to comment Share on other sites More sharing options...
Roger Lee Posted May 25, 2017 Report Share Posted May 25, 2017 Hi Corey, At your elevation the #2 position is too lean and it will cause larger mag drops. Link to comment Share on other sites More sharing options...
CT4ME Posted May 25, 2017 Report Share Posted May 25, 2017 I couldn't see that image... anyone else? Link to comment Share on other sites More sharing options...
Anticept Posted May 25, 2017 Author Report Share Posted May 25, 2017 Reuploaded Link to comment Share on other sites More sharing options...
Runtoeat Posted May 25, 2017 Report Share Posted May 25, 2017 19 hours ago, Tom Baker said: I had the same exact problem with one this past summer after doing a hose change. It is frustrating, because you looking for an ignition problem when it isn't an ignition problem. Tom, your comments indicate you found fuel mixture to be causing a mag drop. Although you don't say it, did you find the clips in #2 positions the same as Corey did and when you positioned them to #3 position, the concern was resolved? Link to comment Share on other sites More sharing options...
Tom Baker Posted May 25, 2017 Report Share Posted May 25, 2017 1 hour ago, Runtoeat said: Tom, your comments indicate you found fuel mixture to be causing a mag drop. Although you don't say it, did you find the clips in #2 positions the same as Corey did and when you positioned them to #3 position, the concern was resolved? That is exactly what I am saying. I found the issue during the post hose change test run. I had not run the engine prior to the hose change. The bad thing is I disassembled the carbs for inspection, and I removed the clip to inspect the groove, and put it back in the same incorrect spot. I realized the issue when I pulled the carbs a part a second time. Link to comment Share on other sites More sharing options...
Runtoeat Posted May 26, 2017 Report Share Posted May 26, 2017 Previous reports have been made about fuel mixture causing mag drops. This confirms those reports. Good info. Link to comment Share on other sites More sharing options...
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