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In a message dated 9/16/03 6:27:27 PM Eastern Daylight Time, [EMAIL PROTECTED] writes: > Is there anything you can think of that could cause the drop or any direction > you could give me in rechecking or troubleshooting? First of all, confirm the mags are installed correctly and timed correctly. The Left mag is supposed to fire the bottom plugs on all 4 cylinders. Many Lycoming type mechanics think it should fire top plugs on one side and bottom on the other. Not so, because the timing of the mags is staggered. Conversely, the right mag fires the top plugs. Next, the timing. The left mag should be set to 30* BTDC. The right mag is set to 28* BTDC. (The authoritative source of these values is the engine Type Certificate Data Sheet) If all this is correct and the right mag and harness and top plugs are all confirmed OK, then it pays to look at the left mag, as someone else suggested. One thing to try is switching mags. Make sure that the mag that's firing the bottom plugs is the one set to 30*, regardless of which side of the engine it happens to be on at the time, otherwise you'll just confuse the issue. (Be sure to put everything back the way it should be when you're done to prevent confusion in the future). The carb is not likely the cause of this problem, but if it is a C75 carb, you'll never make rated power. The throat of a C75 carb is smaller and cannot flow enough air to make 85 HP at rated RPM. RSVP John ========================================================================== ==== To leave this forum go to: http://ercoupers.com/lists.htm Search the archives on http://escribe.com/aviation/coupers-tech/
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