Lean 2 & 3 Cylinders

N2830C · Post by **N2830C** » Sat Oct 04, 2003 4:51 pm

I have owned my 54 170B for all of 6 months now and I just went through my first annual on it. When the plugs were pulled it appeared that the #2 & #3 cylinders were running lean while my other cylinders were running rich. Is this common for a O-300? Any suggestions?

Post by **GAHorn** » Sat Oct 04, 2003 4:59 pm

In a healthy C-145/O-300, the number 2 cylinder runs the leanest/hottest. That's why the CHT probe is installed on that cylinder, and it's why that cylinder's exhaust is the recommended location for a single-probe EGT. If other cyls seem to be running excessively lean (or leaner than #2) you might want to investigate possible intake/induction air leaks in that cyl's induciton system. Dry;loose hoses or broken gaskets are most likely.