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Condition Inspection + New Plugs = Vibration Gone

bkervaski

bkervaski

Hellloooooooo!
Testing
I had a very minor vibration that seemed to exasperate around 2400rpm to which I thought was normal until my recent condition inspection. It was so minimal I've put off getting the prop balanced. But now, it's gone!

The only thing I can think of is that perhaps I mis-gapped one or more of the previous automotive plugs. I can't think of anything else that could have contributed.

At any rate, there's virtually no vibration in the airplane now.

Still very much learning, curious if anyone has a theory?
 
bkervaski said:
I had a very minor vibration that seemed to exasperate around 2400rpm to which I thought was normal until my recent condition inspection. It was so minimal I've put off getting the prop balanced. But now, it's gone!

The only thing I can think of is that perhaps I mis-gapped one or more of the previous automotive plugs. I can't think of anything else that could have contributed.

At any rate, there's virtually no vibration in the airplane now.

Still very much learning, curious if anyone has a theory?
Click to expand...

Were you able to observe a meaningfull EGT rise on each of the four cyl when dropping each mag during runup? a misfiring plug (often don't fail to fire until higher RPMs) would do this. If that were the case, now one of your cylinders should be running at a lower EGT than previously at 2400.
 
Go ahead with the prop balance anyway. I balance about 8-10 props for EAA members each year. I haven’t seen a single one that was in the “good” range to start. Most have been in the .2 to .4 IPS area to start but ended up in the .01 to .04 range when we were finished. .07 is regarded as “good”. You will be surprised at the difference even between .2 and .07.
 
I have run into issues on cars that at higher rpm a plug will start dropping out. Sometimes they do it all the time and sometimes its intermittent. Makes it kind of a bugger to track down.
 
A 4 banger, Horz opposed, big bore stroke engine, any small difference in power between cylinders will cause vibrations... What were your EGT/CHT for the 4 jugs before and after the spark plug change?
 
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