Operating tempuratures of C-85

[nrpetersen]

I've now got about 3 hrs since chrome MOH on my J-4 with it's C-85 engine in a pressure cowl arrangement. The cyl temps on the rear two cyls are running about 400 DegF (both under the lower sparkplug thermocouples) and the oil temp is running about 200 DegF at 80 deg air temps. I built new baffling for it based on C-172 practice with emphasis on getting it tight and rigid to the fins to force all air thru the fins. It has an air outlet flange to increase the airflow as well as side vents ala PA-18. Oil is Aeroshell Grade 80, and there is no oil cooler. There are intercylinder baffles and head intercylinder baffles as common to this engine installation. The oil stays very clean and it doesn't seem to use very much at all, suggesting the rings have seated well. The engine seems loose & broken in otherwise.

Do these temps seem out of line? Cruise airspeed is only about 85 mph so the cooling system doesn't really have a lot of pressure to work with. What sort of temps are any of you seeing on your Cubs and Champs etc w this engine? I realize many may not have CHT.

[D.grimm]

I had those oil temperatures on my Vagabond with a C85-12.
i purchased the PA-11 oil bulb shroud from Univair and added a scat tube
like the PA-11. Oil temp is now 160-180.
Lots of discussion about this at www.supercub.org as to the actual effectiveness.
If it was good enough for the PA-11, it's good enough for me.
Dave

[Mike Berg]

I have an Aeronca L16 (Champ) with a 0200 engine and cylinder temperature gauges on the back two cylinders. Considering this was an 'engine conversion' (0200 rather than a C85) I thought I might have temperature problems but I typically see about 300 degrees at cruise and maybe just short of 400 degrees on a hard climb. Oil temperature usually runs about 160-170 degrees. I have a add on oil filters which may help some with the oil temperature. I cruise about 90-95 at 24-2450 rpm and the Champ does have the pressure cowl setup with the lower lip modification.

[rwanttaja]

Here's an Aeronca bulletin on engine temperatures...you might find it useful:

http://www.bowersflybaby.com/tech/Aeronca%207AC%20cooling.pdf


Ron Wanttaja

[jam0552@msn.com]

Everything I've read on baffling for the C-85 lists a "scoop" beneath the engine case which picks up ram air from the spinner area, runs it just underneath the engine case and dumps it out the rear near the oil tank. It is supposed to cool the oil temp better. I have one installed in my 1940 Funk with a C-85. I haven't flown it yet but running it on the ground the oil temps seem to stay cool. A recent post on Supercub.org showed someone's home made baffle, if you want a picture.
-Joel Marketello