I'm thinking about adding an EGT gauge to my 150/150 for leaning purposes. I always leaned the old 170 to slightly rough, then richened it to smooth- and that worked just fine. However, the engine on my 150/150 is on a dynafocal mount and there is no "lean to rough"- it's smooth right up until it starts to quit.
I am somewhat of a instrumentation minimalist but might have to make an exception in this case. I plan to go with a single-point EGT, and probably an analog version- the digital EGT on my first airplane was very hard to use since the numbers displayed changed up and down so rapidly.
I'm looking for some imput on which cylinder runs the hottest on the 320. Might be different for different installations so I'm looking for a broad range of aircraft types. A friend with a 360 on a Glastar Sportsman sez #4 is hottest on it.

Eric

The answer to your question will depend largely on the installation. Since this isn't a factory installation, you're pretty much on your own.

If you are intent on keeping it really simple, continue to lean till it starts to die, then enrichen it a bit. I've done this many times with EGT equipped Lycoming engines, and found that it's always in the safe range. Not as precise as full instrumentation, perhaps, but it works.

MTV

After running a 4 prob EGT for several years on my 150/150 I found #3 to consistantly be the hottest...both EGT and CHT, which is the most common in many installations. You can't beat a good digital setup as they are dead accurate (and unfortunately many analog gauges are not). I now just use a single probe EGT/CHT dual readout digital gauge and it's on #3 cylinder. For fine tuning the mixture install a vernier mixture control and make all adjustments slowly.

#4 is the hottest on the O-320-E2D in my '74 172M. I run a JPI 700 with CHT and EGT leads on all four cylinders.

hotrod150 wrote:I'm thinking about adding an EGT gauge to my 150/150 for leaning purposes. I always leaned the old 170 to slightly rough, then richened it to smooth- and that worked just fine. However, the engine on my 150/150 is on a dynafocal mount and there is no "lean to rough"- it's smooth right up until it starts to quit.
I am somewhat of a instrumentation minimalist but might have to make an exception in this case. I plan to go with a single-point EGT, and probably an analog version- the digital EGT on my first airplane was very hard to use since the numbers displayed changed up and down so rapidly.
I'm looking for some imput on which cylinder runs the hottest on the 320. Might be different for different installations so I'm looking for a broad range of aircraft types. A friend with a 360 on a Glastar Sportsman sez #4 is hottest on it.

Eric

Eric consider yourself lucky, the reason its doing that is because you have one of the few that has an even induction system.

The one you had before was so uneven thats why you had it get rough.

Just pretend its one cylinder doing it and save your money

[quote="mr scout] ................
Eric consider yourself lucky, the reason its doing that is because you have one of the few that has an even induction system.
The one you had before was so uneven thats why you had it get rough.
Just pretend its one cylinder doing it and save your money [/quote]

I'd like to think that it's even, but I just can't. I have to believe that it's those big soft Lord rubbers & the dynafocal mount.
Since "simpler is better" is one of my creeds, I am inclined to forgo any more gauges if I feel that "leaning by feel" will work OK with this set-up. I'd hate to burn a hole in a piston and find out the hard way that it ain't!
So far I've leaned it starting when I reduce the power after akeoff, but I'm not agressive about it.

Eric

mr scout wrote:[Just pretend its one cylinder doing it and save your money

Bingo, exactly. And to be exact, the hottest cylinder only tells you which one has the lowest compression. You ideally want to lean to the leanest cylinder, that would be the first one to peak, which usually isn't the hottest, and without spending a lot of money on an analyzer your not going to know which one that is. These engines have run fine for decades without fancy instrumentation, and will continue to do so.
I'm usually the guy who keeps improving something until I F*** it up, don't make my mistake.

You guys are probably right-- besides "simpler is better", another one of my creeds is "if it ain't broke, don't fix it". I'll just keep doing it the way I been doing it all this time. Thanks for your imput.

Eric