Hey, y’all. I’m tying to build a r670, 7 cylinder engine for a 1.72 Stearman. I used a piece off a car engine for the crankshaft housing, with some milliput to form the front of the housing. I sourced some breathers from a couple of nascar engines and wrapped them in wire for the ribbing. I think that I have the cylinder angles right, but it looks bare up against the aircraft. The exhaust isn’t on yet, but it won’t affect the look that much. Here’s a couple of pics. Any suggestions you have are appreciated. 
Well I think it’s looking pretty good. My thoughts:
The cylinders are a little long. The crankcase is a little small in diameter, and really is more seven sided. The cam covers should be a little more outside the heads. But I do think it looks pretty good.
The pushrods add a lot. Also, painting of an exposed radial can make or break it, so get good reference photos and take care.
I know that Engines and Things makes the 670 in at least some scales- not sure of 1:72. In the smaller scales those resin engines are not that expensive and can add a lot to many kits.
Thanks for the feedback. G, I played with the crankcase size last night, but it increased the gap between cylinders, even using a wider cylinder size didn’t help. It did, though, make me think that my cylinders are too thin, especially up top. I found a slightly larger radius for a crankcase, and I’ll try again with some wider cylinders. Don, I discovered that the pushrods are in the back, so you’re even more spot on about painting it right. We’ll see how it goes…
Second effort. Punched discs and stacked them. Still needs the rocker covers up top. Better? 
Get a photo of the real engine and use that for guidance. Rocker covers, push rods, Ignition wiring and whatever else you see in the photo. Details you create don’t have to be exact, they just need to look the part.
Oh, yeah baby!
The thing though about the paint finish, look at all the pictures of engines online, then go pop the hood on your F-150 and understand the real thing.
Don’t pay too much attention to derelict aircraft unless you are building a derelict aircraft.
Maintainance procedures and overhaul regs require pretty frequent servicing on aircraft engines, so they appear much cleaner than vehicle engines. Also, they operate in a cleaner environment much of the time- dusty environment only on takeoffs and landings. Engines may have some oil on them, but not a lot of dirt/dust. And the oil is changed frequently (or radials use a lot of oil) so the oil in engines tends to be cleaner than oil on vehicle engines.
I did a search for 670 photos when I built my Stearman, and most of the pics I found were pretty clean- only a few really dirty ones. Also, cylinders are chemically treated or natural machined finish- only crankcase and rocker covers were painted, so there is less aged paint on an aircooled engine, even though they get hotter than a liquid cooled engine.
You are not too far off, the 670 has quite a bit of space between the cylinders. Go to eaa.org and look for pics of our Travelair E4000, Swallow and PT-3. They are all flying with the 220 Continental and none are cowled, so you can see a lot of the engine.
Thanks again for the help. It looks like the wartime birds had black cylinders. If I see it correctly, the exhaust pipes go back into the aircraft. For now, gotta find some rocker covers.
Correct on the exhaust, and it all routes into a single exhaust pipe that exits on the right side. The intakes will enter the cylinder below the other rocker box, and they originate from the backside of the crankcase below each cylinder.
It’s been years since I heard this explanation, but here goes.
Black was the predominant color for the higher heat regions, like cylinders, since it helps to radiate heat away from the surface. I think it was optional, some folks preferred silver colors, that may not have been paint. In some instances the lower cylinder was un-coated, I was told that would help to see cracks developing, as that was a high stress area.
Often the main case was a medium gray gloss, (1) it would show leaks of darker lubricants more prominantly, (2) being a glossy and non absorptive surface, it made the cleanup much easier and faster.
Don S. is correct, keeping the aircraft engine and engine bay clean was quite important, that would help keep the engine cooler, by air flow not being interupted with dirt and fluid collections. Also it would identify and locate a leak much faster, fascilitating the repair before it became a big un-addressed mechanical fault.
Gotta be an A&P rated guy on here, how about some additional info.
Patrick
That old saw about black colors and radiation only applies to visible wavelengths, and even engines do not get hot enough to glow visibly (the exhaust stacks do). All paints are dark in infrared, main spectrum for heat radiation at normal engine temps, but paint is an insulating substance and that is the last thing you need for getting rid of heat. So generally only lower temperature areas of engines were painted.
Black engine colors may be due to natural patina of steel, or a chemical finish with hot oil. Usually black areas were steel, silvery color aluminum uncoated. Black paint is used on some areas like magnetos, etc. Some engine mfgs did paint crankcase black, but black is not a common color for crankcases. PW and Wright generally used gray, some early aluminum crankcases were left natural.
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Thanks again for the information, it’s helping immensely. As an aside, I finished the cylinder assembly. I think that I will paint next, then add the wiring and exhaust, but I’ll probably start working on the cockpit after painting so I can get over the thousand yard stare I’ve developed. 
I agree with Don, it makes sense that paint would actually insulate against heat radiation. The radial engines I had experience with did have black upper cylinders, but in retrospect I recall them having a somewhat natural cast texture, if they had been painted I would expect them to be smoother, as paint does level surfaces.
I’d guess they did have a metal treatment applied, such as for anti corrosion purposes. Well explained, Don.
Patrick
Rather than work so hard at making miltiple cylinders look exactly the same, make just one cylinder and resin cast copies. Tht way they all look exactly the same. I have done that myself and it came out much better and is a lot easier too.
Hope that helps.
SPM, you just gave me my “Doh!” moment. I think that I will need to redo the cylinders again, it looks a little large on the nose of the Stearman now. I’ll go that route if I do. Thanks!
Cylinders and cylinder blocks have traditionally been made of cast iron. It combines low heat distortion, lower cost than aluminum, and high durability.
Because of it’s relatively high carbon content, it doesn’t readily oxidize, and has a natural flat black appearance.
Was this with liquid cooled? I think most cylinders on aircooled were steel, and machined on outside. There were also some that were aluminum with steel sleeves.