Does anyone know what engine baffling was factory standard in the 40's for a Continental C85? I acquired an old Luscombe 8E and it has a "shroud" around the engine in addition to the normal baffle seals around the cowling door. I have seen a diagram of the pieces used to make it on one of the Luscombe sites, but not sure if it was a later modification. The shroud makes it more difficult to inspect the engine and pull plugs etc.
Also, the cylinder head temp gauge is marked 250 degrees redline. Seems low to me, compared to the bigger Continentals I run. Anyone know if it is accurate?
Anyway, if the tighter shroud arround the engine promotes better cooling, I will leave well enough alone. Just curious about it, since I see in many Luscombe photos... the absence of any additional sheet metal around the engine. Thanks in advance for any comments.

The Cessna 120/140 assoc site has a technical article section. There is a article about inter cylinder and oil tank baffles. My Cessna 120 1946 with a c85-f12 looks like the articles. Not much fun taking everything off. Mine is a cool running c 85. So I have lots of tape(my winter kit) on the front to get and keep the oil temp to 190. Cylinder head temp is about 150 C. most of the time this time of year.
ML

The Continentals came with a soft aluminum baffle that was sandwiched between the intake spider and the bottom of the crankcase. It fits over the two long studs that mount the spider. This baffle forms a channel underneath the engine, where air (from a hole in the nose cowl underneath the crankshaft) flows along the bottom of the engine. This baffle is important and has a large effect on the oil temp.

The Continentals use the bottom of the case as the oil return path. It drips down the inside of the case, then runs along the bottom, and pours back into the oil tank. So the entire bottom of the crankcase on the Continentals is the primary oil cooling method. If you blow cool air on that aluminum crankcase, the oil transfers its heat into the aluminum, then the aluminum gets cooled. Result: lower oil temperature without the hoses and cost and complexity of a small oil radiator.

The problem is... this lower case baffle needs to seal against the sides of the crankcase so the air does not just squirt out the sides. So the edges of this baffle must fit tightly against the engine, and it is a weird shape because of the shape of the lower engine case. So you need to make sure that baffle is there, and then make sure it is sealed against the sides of the engine. THEN, you need to make sure this air passage is sealed to the front of the engine and the inside of the nose bowl. THEN you need to make sure there is a small "roof" section to this duct just in front of the engine case. Some airplanes have this upper duct, some don't. But putting the roof on the duct (so that air coming in from the dedicated oil cooling hole in the nose cowl cannot just come in and then go upward into the main upper cooling plenum chamber) is a sure way to lower the oil temp. If you need further explanation and/or photos, let me know. But right now, most of the country is not exactly having high oil temp problems

EZ flapper..... thanks for the explanation of all the metal, and where all the air goes.
I think I actually need to get some tape on it this time of year to get the temps up... but come summer in Arizona the baffles will help.
I appreciate you taking time to explain so thoroughly !!!
Cheers

The baffle issue is well covered, and I learned from that, too.

Re: CHT, you didn't state the units, I'm assuming Degrees Centrigrade (because Celcius hadn't been invented yet ), so that may be valid, or may be just how an old gauge was marked. The big thing is, small Continentals didn't have a proper CHT point, i.e., a well near the exhaust port, so run off of a sparkplug washer. There's no factory data for how that correlates to actual CHT, so flaky data point. The SkyRanch engine manual has a decent discussion of this issue.

That said, I hope you enjoy the HECK out of your Luscombe: I know I sure did with mine.

Thanks. cubscout

Not sure I understand what you mean by the "shroud" that is around your engine but this is the factory baffling on my 8E.

Shroud...you're not talking about a cooling plenum, like this are you?



That would seem odd on a Luscombe.

cubscout wrote:There's no factory data for how that correlates to actual CHT, so flaky data point. The SkyRanch engine manual has a decent discussion of this issue.

Well... take this with a grain of salt... but this comes from personal experience: The CHT on the hottest cylinder on an A-65 Continental, in a relatively stock Taylorcrtaft, on climbout on a warm day - can read 450F. I had one of the few T-crafts with a four-probe CHT installed. I am certain that this is one of the reasons they did not offer CHT's in T-crafts.

Take this with a grain of salt too, but again this is personal experience: The Continental O-200 cylinder will live approximately four minutes above 550 degrees F, and fail catastrophically at 625 degrees F, when flying at approximately fifteen feet AGL and 240 miles per hour in loose formation with seven other experimental aircraft, in the immediate vicinity of Stead airfield in waivered airspace. This is not a recommended procedure for recreational flying

IMHO the target CHT for the small Continental engines should be about 350 to 375 F. A little more than that on climbout on a warm day is completely acceptable and safe, so long as you have oil temperatures below 240F to prevent the oil's lubricating properties from breaking down. Unfortunately, the sparkplug type CHT gauges are notorious for reading incorrectly. So in my experiments I used the "temp-a-dot" stock on dots that change color with temp. And I found that the hot cylinder was indeed hot... reaching well over 400 F.

The problem is that most of these little airplanes have marginal cooling system designs. The place where the cooling air comes in, and goes out, are far far less than ideal. You have a lot less flow-through than you need to absorb and carry away the heat. If anyone is having serious heating problems, and is more concerned with solving the cooling issue than the paperwork issue, I can tell you how to solve it. But you're on your own with the paper.