Experimenter is a magazine created by EAA for people who build airplanes. We will report on amateur-built aircraft as well as ultralights and other light aircraft.
Issue link: http://experimenter.epubxp.com/i/113663
Un d e r t h e C o w l Asking a seller to remove the valve covers isn't asking too much. Buying a Used Lycoming By Tim Kern Among the most popular engines for experimental amateur-built (E-AB) aircraft are the four-cylinder Lycoming engines of 320 and 360 cubic inches. Their popularity comes from several directions: Their availability in many models means that there is a good engine match for many airframes; their long history of development leads to greater "tribal knowledge" and confidence; and their sheer numbers bode well for low prices. Their very familiarity, though, can mask or even create some tempting pitfalls. Parts swappers don't always get good results. For example, putting high-compression pistons from a 160-hp "D" model into a 150-hp O-320-E model won't work. There's simply more to swapping parts than that. The O-320-E, with its lower compression, is cheaper for a reason; its iron barrels and narrower nose bearings are adequate to the task of producing that 150 hp. Hotrodding it won't give you the 10 nominal horses the model difference would, but a new set of rings and a valve job very well might add 10 horsepower to a tired one. The 320 series, specifically, has a little caveat in that it was made in "wide deck" and "narrow deck" engines. The older narrow deck engines are just fine to use, but their parts are 36 Vol.2 N o.3 / M arch 201 3 getting scarce. How can you tell? The wide deck engine has an "A" at the end of its serial number; the narrow deck doesn't. Even close relatives have differences. The notion that a "360 is a 360" isn't even remotely true; there are angle-valve and parallel-valve versions, solid and hollow crankshafts, and a myriad other differences. An old post once available on Primemover.org noted that the O-360-A1A "has a bottommounted updraft carburetor, parallel valves, 8.5:1 compression ratio, and produces 180 hp." Yet another post stated, "The IO-360-AlA features a horizontal front-mounted fuel injector, angle valves, 8.7:1 compression ratio, and is rated at 200 hp. The IO-360-A1 also incorporates these design items, which are not included in the O-360: piston cooling nozzles, stronger crankshaft, tongue and groove connecting rods with stretch bolts, tuned intake system, and rotator type intake valves." The lesson? If you don't know what you're looking at, contact a real expert. All the engine builders that I talked with for this article said this: Keep the engine close to its original configuration, and don't swap significant parts. Photography by Tim Kern