I have one Slick mag set to 25 degrees and the EC3 timing was previously set to 25 degrees with the engine running at WOT, on the ground. I have 9:1 pistons, LS1 coils and Magnecor racing plug wires. Electromotive 1/2" sensors.
Yesterday, I replaced all the automotive plugs with NGK 3035 (was Denso Iridium IK27, but no local sources) and cleaned the aviation plugs - no help.
I braced the sensor support bracket - no help.
I checked and adjusted the runout of the trigger wheel to .003" - no help. I have .030" air gap between the sensor and the trigger wheel.
Today's symptoms, in flight. 5,500' msl, 6,500' D.A. OAT 62F
At WOT and ignition set to BOTH, I only get about 2,950 RPM (should be 3,100 with this prop). The engine is fairly smooth but I have seen it smoother.
On MAG only the RPMs drop about 100 RPM, but remains relatively smooth - for running on a single mag.
On EI only, I get a BAD miss. Adjusting the mixture from full rich to lean seems to have no effect.
I think that's about it. How do I fix this?
4 comments:
Sam, When you are flying at WOT with your mag off you get a bad miss. With mag off, when you reduce power in flight, at what RPM does the miss go away?
Mike B.
Sam, When you are flying at WOT with your mag off you get a bad miss. With mag off, when you reduce power in flight, at what RPM does the miss go away?
Mike, it's somewhere around 2,600 RPM.
Sam, the backfire you had when switching mag off could indicate your electronic ignition timing is way out of whack above 2600. I'm sure you probably checked this, but I would bet your miss is something simple like this. Could your electronic ignition be retarding the spark as Rpm increases instead of advancing it like it is supposed to? maybe something is backwards?
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