View Full Version : O-320 CHT

Al King
10-05-2004, 08:54 AM
I just got my Northstar flying again after a year apart and some repairs.
What is considered normal cylinder head temperatures for an O-320.
My temp sensor is under the lower plug on #4 and I am getting about 375 to 400 in cruize and almost 500 in a continuous climb.
This seems hot but the overhaul manual says 500 and a local AME says 400 in cruize is OK. The OAT is about 60 f
I'm curious as to what most cubs get in this way.

10-05-2004, 10:16 AM

That, while within limits, seems pretty darn hot. I expect to see high 300's in cruise, and rarely if ever over 400 by much, even in an extended climb.

Course, I live near sea level, and in cool country. If you are at high altitude, your results WILL vary.


10-05-2004, 11:01 AM
Remember Alan...under the plug thermocouples generally read 25 to 50*F hotter than if you had a bayonet thermo screwed into the proper thermocouple hole under the cylinder. Howard had this "problem" with his O-320 of touching 500*F in climb (as did many others on the Rebel list) and when switched to bayonet thermo's this "problem" disappeared with nobody getting over 450 in hard climb.

Also give that freshly assembled engine a few hard hours and you will see the temps drop about 50* as well !