cessnapete
31st Jan 2011, 08:11
I am thinking of fitting a single channel EGT gauge onto a vintage Cessna 180 with a Cont 0-470 carburetted powerplant. Which cylinder would be most suitable for the probe.
We already have a CHT gauge fitted and would possible retrofit a dual CHT/EGT display.
SkyHawk-N
31st Jan 2011, 10:18
You want the single EGT probe on the hottest exhaust. I seem to remember that on the 0-470 the front two cylinders run the richest so your choice probably remains with the other four.
Teledyne/Continental have a service bulletin (#M89-18) which recommends leaning practices and EGTs/CHTs, that MAY provide information that can help you.
Pilot DAR
31st Jan 2011, 11:04
You will likely find that the hottest cylinder on a 470, or most carburetted engines, is literally a moving target. I had a six channel scanner installed on a carburetted IO-470F back in the late 80's, and found that the leanest cylinder was not always the same one, and varied with power setting. The induction balance tube (across the front of the engine) also had a lot to do with this. There are three sizes, and when we removed the injection, and went carburetted, we had to do a lot of fiddling with this. My current experience with my O-200 with a four cylinder bar graph bears this out. I set power first, then lean to the leanest cylinder.
This is one of the reasons for fuel injection becoming popular, in that the fuel distribution is more precise than carburetted induction systems. Fuel injection systems are not so popular with those who would like to use MOGAS.
So, either install the single cylinder probe, and lean conservatively, or go the extra, and install the six cylinder system (bar graph better). From a CHT point of view, you'll pobably be happy that you installed the six cylinder system as well - interesting indications there too!