J

johnpaul44

Member
Lycoming O-360-A1A
10–4164 carb
dual p-mag
fixed pitch

Im trying to chase down a single egt that is high only a full throttle so far i have:
replaced egt probe
all new plugs/wires
replaced all intake tubes, new intake flanges, new gaskets with permentex added to gaskets

at full throttle only my cylinder 1 egt will spike to 1350 or so degrees while the other remain the same. As soon as i reduce from full throttle the egt begin to even out. when running lower power and leaned out egt spread is very close.

see the savvy report below: i tried a lean, rich , lean test at constant MAP at altitude and all egts were about a 300 degree spread or so

https://apps.savvyaviation.com/flights/shared/flight/7526260/d8820ce2-ba6a-463c-9274-cc4198de44c7

whats going on here?
 
Have you stuck a camera in there and moved the prop to check what the valves in that cylinder is doing?
 
I'd also check plug leads and change plugs (especially since they are so cheap). One plug not firing will result in a high EGT as the gases are still burning on their way past the EGT probe.
 
The carburetor supply liquid fuel to the air stream.
The weight (mass) of the fuel is much heavier than the air.
With increased air velocity the distribution/ mixture of the fuel to the cylinders will be less exact with a carburetor. You could try with a larger main nozzle.
This will increase the fuel flow but will not change the distribution much.
A fuel injected system will provide better fuel distribution to each cylinder.

Good luck
 
At full throttle, try pulling carb heat and see if there is a change.... Wait for it. That may give you a clue.
 
I came across your post and clicked on the Savvy report. Your EGTs and CHTs look similar to mine. I also have a Lycoming O-360-A1A with a 10–4164 carb, C/S prop and one slick and one SureFly mag set to advance timing based on manifold pressure. EGT 1 and CHT 1 runs higher than the others. I'm still working with Savvy to upload my data. I plot my data myself using excel. Did you find come up with a way to reduce the temps?
 
dnickerson46 said:
I came across your post and clicked on the Savvy report. Your EGTs and CHTs look similar to mine. I also have a Lycoming O-360-A1A with a 10–4164 carb, C/S prop and one slick and one SureFly mag set to advance timing based on manifold pressure. EGT 1 and CHT 1 runs higher than the others. I'm still working with Savvy to upload my data. I plot my data myself using excel. Did you find come up with a way to reduce the temps?
Click to expand...
The only thing I found was to pull throttle out slightly above 1000 feet agl or so and the temps get more even.
 
Before you chase your tail too far. Try swapping the entire suspect sensor assembly with wire to another cylinder. If the problem follows, you'll have an answer. If your issue with the temperature remains with the same cylinder, you'll have a different answer.
 
Is there any other indication of a problem? Valves look okay on borescope? Compressions good? CHTs okay? Engine running smoothly?

I don't know for sure but I can imagine a scenario where the gas flow simply hits the probe differently at full throttle depending on the curve of #1 pipe, orientation of the probe in the pipe, or any one of a number of factors. If there's some other indication that there's a problem that would be another matter, but otherwise I'm not sure I'd worry about it.

Just my opinion, might be worth asking SavvyQA if you have an account.
 
You must log in or register to reply here.