CHT

[WingsOnWheels]

Originally Posted by hecilopter

Just wanted to point out something I haven't seen posted here in this discussion. When you are setting your timing, you find TDC on Cylinder #1, make sure the timing mark for TDC on the back of the ring gear is aligned with the split in the case half. Then proceed to rotate the prop counter clockwise in its normal rotation until you hear the impulse coupling "snap". THEN back the prop back up to the 25 degree mark on the back of the ring gear aligned with the case half and the mag growler light should come on for both mags. Just hadn't seen anyone mention unloading the impulse coupling before setting timing.

Rusty, thanks for the advice. Yes, I always make sure the impulse coupling is released when setting the timing. I've checked the timing almost 5 times at this point.

[ppakotze]

Hello

20hrs into flight testing IO-360 A1B 200Hp.

Amongst other niggles had high oil temp and high CHT. Discovered EFIS setup issue when I dipped CHT thermocouple into a kettle *while* it was boiling. Compared EFIS temperature to a multimeter with a thermocouple. Discovered EFIS overreading by 40 to 60 F. Discovered I had the wrong type of thermocouple selected for what was installed (I had J type and EFIS assumed K type). Selected J and now CHTs very much believable.

Regards
P.

[jrs14855]

Reference post #71, the prop should be turned backwards slightly past the 25 degree mark and the moved slowly forward to the 25 degree mark.

[WingsOnWheels]

Just some follow-up. Passed 40hrs recently. Same cooling setup. I tested with and without my inlet seals, then with and without duct tape in there place. I don't have a manometer setup, so I cant accurately quantify the results. Based on general observations, I would say the duct tape provided the best cooling flow, but only very slightly if any over my original setup. Without any gap seal was noticable, probably worth almost 10 degrees on climbout.

At this point I am back to my intial setup, It appears the engine just needed some more break in time. Temps have dropped quite a bit. In climb, 1&3 are still my hotter cylinders. I will still work to improve cooling, but it is acceptable now. EGT sensors are still entirely unreliable. Even with new proper thermocouple connectors. I am going to pull them all at the next oil change and play with the wiring.

Note, on this flight I did not have my nose wheel pant or leg fairing installed (finishing paint).

Power pulled back, temps even


Wide open, you can see 2&4 are good, 1&3 are a little hot. But much better thsn before.