The International Cessna^® 170 Association

Got a ? about EGT (lil ole indicator way over on the right), Does anyone pay any attention to it?
What is the maximum temp we should see? Full rich to lean will be 25*-50* difference.
Nothing in my owner's manual.
Anybody got their $0.02 worth to put in?
Thanx

Phantomphixer
N3585C
Somerton, AZ

The problem with a single EGT is it only tells you what is happening at that cylinder. You have no idea if that cylinder is representative of the other cylinders or not. Theory is it is suppose to be installed on the hottest cylinder. Suppose to be being the operative words. How would you know?

If your EGT is reading on what is normally the hottest cylinder, you can pretty well not worry about the other five. If you're flying at 7,000 ft. MSL, or above, there is little possibility that you can pull enough power in a lean mixture to equal about 75%, the kind of danger point where you can overheat your cykinders.
If you get down in the 70% range, there is no way you can over lean to a too high combustion temperature and damage your engine.

A common way to lean these engines is to set power for whatever condition you are flying then slowly lean the mixture until you feel the power start to fall off or it starts to run slightly rough. Then enrich the mixture just until it runs smooth. That insures all of the cylinders are producing power as well as the built-in uneven air-fuel mixture distribution will allow. The actual EGT temperature is irrelevant and makes no differernce, the engine will tell you by feel when it is happy.

Like BL says, below 70% you can't hurt the engine by leaning.

phantomphixer wrote:Got a ? about EGT (lil ole indicator way over on the right), Does anyone pay any attention to it?
What is the maximum temp we should see? Full rich to lean will be 25*-50* difference.
Nothing in my owner's manual.
Anybody got their $0.02 worth to put in?
Thanx

Phantomphixer
N3585C
Somerton, AZ

"Way over on the right..."...??? WHAT does that mean?
Ans: Not much.

Is your EGT gauge compensated? or not-compensated?
Is it merely "relative reading" or "actual temperature"..??

Is the gauge calibrated? or not?

Chances are... it doesn't mean much in this engine.

Follow the Owner's Manual technique for leaning and let it be...

hey we are in the 21st century, lets use whats now available. its my belief ,I have saved heaps of fuel and time in using the latest instruments . I have a fuel flow computer[it also tells me how much fuel that has been used and whats left in the tanks] and I lean towards 34 to 36 litres a hour and watch the CHT,s also as they average out to about 340 deg and my EGT which is 1400 deg . the GPS is used foremost but a paper map is used at the same time and marked accordingly. the gps has created a situational awareness that is second to none. one gets to know what one expects from each cylinder and if some thing is different you keep a eye on it . recently I had a intake gasket crumble and the engine ran fine ,CHT on the cylinder was a couple of degrees hotter which was nothing to be excited about BUT the EGT showed me that cylinder was running lean.

Yes, I agree as well, and I have all that stuff in my plane but Phantomphixer was just asking about leaning and EGTs. What I have found with my plane is once I lean it like described above, the fuel flow is 7.2-7.7gph and EGTs are lined out as even as they can get. CHTs are never a concern on my engine.

I do agree the 6-position EGT/CHT monitor is a very good diagnostic tool if a problem arises but not everyone has one (or wants one).

If you had been running on the lean side of peak, a leaking intake gasket would not have caused a rise in EGT, It would have caused a cooling in that cylinder.
If you're down to 70% power and you lean to where the engine begins to stumble and then enrichen just to smooth, tou will be on the lean side of pesk.

A six point is a different animal than a single point. With a six point a live comparison can be made between cylinders with can give useful info a single point can not.

I would not bother to buy/install a single point. I would not bother to buy a multi-point unit but unike the single point unit, would install it if someone gave me one.

I have found some of my old trip logs when I first got the aircraft and those days didn't have the digital instruments that I now have . On a 2.5 hr flight , on the average used 100 litres for the trip . Now days I take 2.3 hrs for the trip using GPS . The GPS allows me to finely fly around a "no fly zone " . OMG. The fuel consumption has dropped down to 90 litres for the trip. I still fly at the same height for ATC reasons.
Please note these figures are a average of about 15 flights . Due to a season , the winds shift and I have tail wind most times

This airplane/engine combination was produced at a time when EGT gauges were for high-tech bombers and airliners, and small planes were simple and leaned according to the tachometer and the pilot's "ear". No problems regarding EGT developed until EGT gauges were installed.
Think about it.


(PS: I have no EGT gauge. None of the TCM-powered Cessnas I flew for thousands of hours while flight instructing and on pipeline patrol had EGTs. (IF they'd had them we wouldn't have had time to look at them anyway.)
It's sort of like Lindbergh's flight.... he made it all the way to Paris within ten minutes of when he said he would with a compass and a clock.
The jet pilots I train today cannot seem to do simple, steep turns without a complete crew-briefing and having a copilot crank the heading-bug around in the direction of the turn prior to the maneuver.

bluEldr: Aren't you glad you did it when it was a real aviator's world?