my O-540-J1A5D runs very strong and very smooth-BUT.....
at a 65% cruise at low altitude i cannot seem to lean it very much at all before the #3 cylinder peaks its EGT. and while #3 is peaking, the #6 cyl is usually around 200 degrees cooler, with the other 4 hovering in between somewhere. (6 probe egt)
i can't do much (if any) leaning until i get up above 3500' or so. and i don't go up there very often.
i lean actively in the pattern and on the ground, and my plugs don't usually have all that much lead fouling. and i just checked the #3 plugs against the #6 plugs today. they all look very similar. and i scrutinized the intake tubes/gaskets at annual for leaks, with none found.

i just wondered if other carbureted 540's operate similar? i realize its not injected- hense the large temp spread. but i'm just checking to make sure i don't have something else going on in there. and it has been single digit temps here for quite a while. i guess that has a lot to do with it.
anyone else have a noticeable increase in GPH with a decrease in temp?



thanks gang....

Is your 65% taken from the Lyc engine manual re. MAP and RPM modified for temp and alt. Is your fuel consumption in line with the graph in the manual. If so then the spread of 150deg -200deg is what I'd expect.

I run a O-540 B4B5 with a 6 point EGT and CHT. My engine runs exactly as you desribe. Over the last year of research I have talked to several others that get the same type of readings. I've come to the conclusion that's the nature of the beast.

Rick Geiger

My O540-J1A5D does just the same. I'll sometimes notice the EGTs all even out when I pull the power back to 15inches for a descent.