[flyrv6a2001]

I fly a RV4 with a 0-320 E2D 150hp. On climb out and full rich, my #4 CHT is about 75 degrees cooler than my highest CHT which is #3 cylinder. #4 is usually around 290-300 and #3 is usually around 360-380. #1 and # 2 CHT's are within 25 degrees of #3 CHT.
Is it ok to have one cylinder to run that much cooler than the other 3 ?

 

[aerhed]

Try the same climb and pull the throttle back just a hair. Moves throttle plate while still staying in the enrichment zone. Might change your distribution enough to move your temps around. I don't think you have a "problem" as long as it sounds/feels good.

 

[RV10inOz]

I have seen this on an RV9A with IO320 recently. It must be baffling.....and confusing too!

The fact some are quite low would suggest airflow is what you should be looking at.

Try a bit of carbie heat as well as pulling the throttle just a bee's whisker, and using a serach function see my recent posts about carby heat and fuel / air distribution. It might help.

My money is on the baffles.

 

[Lycosaurus]

Defective CHT probe

... my #4 CHT is about 75 degrees cooler than my highest CHT ...

I had a similar issue where one of my CHT probes was reading high during cruise but was fine at room temperature.

Swap the #4 CHT probe with another cylinder probe. If the high CHT temperature symptom follows the probe then you know the probe is at fault.

My money is on a defective CHT probe