Getting the mixture right?

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Since the local elevation is about 6500 feet and the trike was originally set up at a somewhat lower altitude, It was not surprising to find a lot of carbon buildup on the plugs after 6 or so hours of running.  I changed the main jets from 165s to 158s and that seemed to make for better running at higher rpm without higher EGT.  Idle and fast idle were still rough so I moved the needle clips up to the next to leanest groove.  This improved smoothness at high idle alright but EGT went up, particularly at cruise RPM.  So I backed down a notch.  At this point, the fact that one side of the Dual EGT was reading hot while the other was not came into play. (This existed from the time I first saw the trike run.)  Switching probes from one side to the other did not change which gauge side read high versus low so that pretty much meant it was a gauge problem.I tried to use the gauge from the Redback 503 but the connectors were wrong.  I tried to use the probes from the Redback but they were a different size.  Finally I found out I could use the exhaust manifold bushings from the 503 on the 582 so I could use the 503's probes and gauge.  To my surprise, I still had the same problem.  One side of the Redback's EGT persisted in readying high.  So which reading was right?  I finally rigged up a digital DMM that had a type K T/C input and attached it to a leg board.  Turned out that probes on both sides were showing about 1275 at cruise rpm (5400).  So, I took the needle clips back to the lowest level.  This brought both probe readings to around 1165 in climb and 1185 in cruise.  Now to get a good replacement dual EGT gauge.

In the process of pulling the top of the Outback's carbs, I noticed the O-rings were badly cracked.  I thus stole the O-rings from the gyro to fix this problem.  I think I now have 7 Bing 54 carbs.  I ordered 4 carb seal kits which just arrived so the gyro MZ engine with get its carb O-rings back shortly.  The Mallard 447 will also get a new throttle cable boot.

In the process of this testing, we are now up to about 10 hours on the rebuilt engine and about 50 landings.

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This page contains a single entry by Cavlon News published on February 10, 2013 10:28 AM.

582 outback trike on ground ready to fly was the previous entry in this blog.

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