Cool Cylinder

[N9657]

I recently had installed a EGT that reads individual cylinders. I am getting No. 2 cylinder about 130-150 degrees cooler than the others. I have a Lycoming 0 360 C1 F. I get these readings at 3000 ft with 75% power. Three clynders are reading about 1540. No. 2 is reading about 1420. Is there any need for concern. I have already switched the probes and No. 2 is still the coolest. The difference is less at lower power. Any suggestions?

[rjb]

My EGTs don't show such a difference but I keep asking about
my cylinder head differences and every response I have gotten
so far is "That's what you get with a carburetor engine".

My JPI run from a flight where I was trying to do some glides for
info into AOPA performance spread sheets:
E1 E2 E3 E4 C1 C2 C3 C4 DIF CLD OAT BAT FF USD RPM MAP HP
MIN 949 984 822 913 102 82 79 92 13 -174 15 14 0 0 823 6 10
AVG 1307 1294 1266 1294 332 322 337 288 50 -15 17 14 8 5 2063 19 57
MAX 1518 1414 1437 1476 418 383 413 360 204 0 23 14 17 10 2694 29 95

-Dick

[maules.com]

A spread of 150 degrees is quite normal for a carburetted Lyc., whereas 70deg is more likely on an injected model.
Running that O360 at 1540deg is higher than I would feel comfy with.
1540 is a peak number I suspect.
There are many variables for each cylinder between the mixing of air and fuel at the carb and the burn point in the cylinder and the exhaust stroke.
Fuel for the injected engine is introduced at a more measured ratio into the air, just at cylinder entry.

[a64pilot]

The difference between cylinders isn't relevant. It's the fuel flow at which the cylinders peak that is important. In other words if they all peak at about the same time, that is more important than the temp at which they peak. Unfortunately, I know of no way to "balance" a carbureted engine.
I'm sorry, I can't make sense of the numbers you posted, it's too early in the morning, but one reason for a cyl head temp difference is if you have one temp transducer that is under the plug where the others are in the head.

[andy]

I've had a JPI EDM-800 in my 1986 MX-7-180 for about 6 years. I have every sensor made for it and I consider it one of the best investments I've ever made. Recently I had to replace one of the EGT probes because one cylinder was reading 300 degrees lower than the others. The sensor was the problem. During installation and later exhaust system replacement, I was very careful to drill the sensor hole exactly 3" down from the flange on the exhaust header on every cylinder. Even a small variation in that distance can throw off the readings. Each cylinder is different and their positions in the engine compartment result in different temperatures, so there will be normal variations between them. I wouldn't worry about a 100-150 degree variation. I prefer to lean using the 50 degree rich of peak method but keep the EGTs under 1500 F.

Andy