What CHTs in climb are acceptable?

[FloridaMan]

After annual and a remanned cylinder this year I am now seeing higher CHTs than I ever have. Previously, it was impossible to get them above 380 or so, even on a hot summer Florida day taking off with cowl flaps closed and climbing at Vy and 2700 RPM. I suspect possibly a baffeling issue. I've done an oil change so it's no longer running the mineral oil. Now they will accelerate to 400 by 1000 ft with the cowl flaps open so I reduce my climb and pull the prop back to 2500. I've had some guys tell me up to 415 is fine. Lycoming says that 435 is ok in climb with keeping them under 400 in cruise. What are you guys seeing? 

[Shadrach]

We fly the same AC. My experience matches your pre replacement experience. My CHTs are always in the low to mid 300s in climb and high 200s to low 300s in cruise. My I ask what cylinder was replaced and why?

Certainly could be a baffle issue. I have been amazed at how many times I've had to reach in and "dress" the baffle material so it is facing forward after the cowl has been affixed by someone who should know better.

[PMcClure]

Different plane and different engine, but I had a similar experience with my CHT. Found timing was advanced. After correcting CHT dropped significantly. 

 

[rbridges]

I try to keep my CHTs under 380.  In fact, I shoot for 360.  I've seen a few articles mention 380 as a safe number for engine longevity.  Are you sure it's not a probe/sensor issue?

[ArtVandelay]

Above 380 I lower nose to get extra speed, at 400 I would go full mixture and lower nose some more.

[M20F]

If it is all the cylinders all of a sudden after an annual going up 40-50 degrees than I would guess as others some type of timing issue.  Have you discussed the issue with the AI that did the annual?  Do you have any additional engine data to share (EGT, fuel flow, etc.). 

 

[FloridaMan]

7 hours ago, Shadrach said:

We fly the same AC. My experience matches your pre replacement experience. My CHTs are always in the low to mid 300s in climb and high 200s to low 300s in cruise. My I ask what cylinder was replaced and why?

Certainly could be a baffle issue. I have been amazed at how many times I've had to reach in and "dress" the baffle material so it is facing forward after the cowl has been affixed by someone who should know better.

 

#4 was replaced due to an engine failure on takeoff at 200 ft caused by FOD in the #4 cylinder destroying both spark plugs. I put it down in a field at the end of the runway. 

[Shadrach]

Well done on the landing. If there's a thread on that, I hope to find it. 

Interesting engine failure...How does FOD enter the combustion chamber? Was it identified? I digress... As 20F says above, if all cylinders are reacting this way, timing would seem the most likely culprit. But then whay would the mags get retimed for a new cylinder? Does the engine feel strong?