Robin,

I'm posting this just in case you read something here that reaches out to you.

I'm having a problem with mixture settings, and idle since coming out of annual.  I'll try to give the play by play with what we found so you can follow along.  Be advised this will be lengthy.

Came out of annual - did run up prior to take off, pulled throttle back to idle, engine stopped. 

After some work with the idle and mixture controls we managed an idle of about 700 RPM that seemed to shake the plane more at idle than it did prior to the inspection.

Flew home all was fine.  Next long flight was to NY where I had the throttle stick in flight in the open position.  I pulled it back - stuck, pulled it again -stuck, pulled it even hard (no comments Scott) - and it broke free with a bit of a snap.  When I landed and pulled the throttle back to idle the engine shut down an would not start even while the prop was windmilling.  I played with some settings and found I could lean the mixture about half way and get the engine to fire.  I thought maybe something had been binding in the quadrant area so I disassembled but didn't find anything.  Did a run-up prior to departure and checked full throttle and idle. Full throttle was developing 27 inches, but the throttle lever travel didn't seem to be as far as I remembered.  When pulled back to idle, the egine would shut off, so I noted a setting that seemed to work for idle.

Next day flew to place that did the annual, Sven was able to stop in on his way to Michigan and assisted.  He immediately noted my mixture was running was lean - this setting was causing a binding toward the rear of the casing (cause of throttle stuck in flight)

After further inspection we found the air box wasn't quite sealing in the cold position.  We could not adjust to limits.  Upon even more detailed inspection we found the mounting clamp for the air induction cable was in the wrong set of mounting holes (about 1/ inch apart) which wasn't allowing us to adjust the alt air box to specs.

The A&P believes that the improper setting on the air box was allowing hot air in the intake which was causing the engine to run rough and rich.  Their leaning out of the mixture to correct the problem caused the binding of the linkage.  We fixed the alt air cable, and re-adjusted to 700 RPM's and re-adjusted the mixture.

Next flight was to Michigan, and after two or three landings the plane would shut off at idle again and the mixture seems to be off.

We adjusted the idle setting by 100 RPM's to about 850.  Helped, but plane is difficult to shut down without adjusting the throttle and the mixture.  In better words pulling the mixture back doesn't shut the plane down I need to leave mixture rich and pull the throttle back to stall the engine.

It was suggested that I open the airbox and look at the impact tubes on the throttle body, I did that yesterday and all seems fine. 

Next I need adjust idle and mixture and am looking for some pointers. 

Also, any ideas why this might keep changing?  Could the mixture wheel be moving in flight?  Should I adjust and then loop some safety wire over it?  Am I missing something very important? 

Dave & Kathy
1975 112A
N1247J ser#247
Reading, PA (RDG)