Static RPM and idle cutoff

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ghostflyer
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Joined: Mon Apr 21, 2008 3:06 am

Static RPM and idle cutoff

Post by ghostflyer »

During my SIDS and 100 hrly I found my compressions on one cylinder down to 45 over 80. These are new cylinders. The air was rushing out of the crank case . I was not happy . With cowls off and carburettor open to the world I was going to ground run to get the engine really hot and lean. I was suspecting broken compression rings . I was going to do another compression check on that cylinder when red hot. the oil Color was like honey with about 26 hours on it. So it wasn't oil control rings . Plus I had only used about a litre of oil in that time. After warm up ,max power was applied. Normal static RPM is 2280. BUT to my surprise the engine revved out to 2550RPM. AND if leaned out it went up 2600RPM. So my attention was when at 1000RPM and idle mixture pulled to stop the engine would I get the 50 RPM rise. Yes 50 RPM rise at stoppage .
Compression check done and cylinder is now 76 over 80. YAWHOOOO. So why the static max engine RPM increase without ducting and air filter. [new filter was fitted] {NB> engine is Lycoming clone 180HP with fixed pitch sensenich prop 60in pitch.}
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