O.S. Engines .40 LA Sport Product Review

O.S. ENGINES .40 LA
PRODUCT TEST REPORT
by Brian Lee

Perhaps the most striking feature of the O.S. .40LA is the fact that it can be ordered in either of two different colors. The natural aluminum finish is available, of course, but you can also get it in an anodized dark blue finish, like the one reviewed here. I recommend the natural finish for two reasons. First, it costs less. Secondly, the very attractive blue finish creates an odd-looking color mismatch, since the carburetor and muffler are not blue, but retain their natural aluminum finish. Either way, however, the color is strictly an external cosmetic feature, and does not effect the engine's performance.

Another remarkable feature of this engine is its low price. For an O.S. .40 size engine, the $99.95 list price is remarkable, and we have seen this engine discounted as low as $49.99 in some mail order ads. And that's with muffler, but no glow plug. And no, I have no idea why O.S. 2C engines and so many others continue to come without glow plugs.

O.S. Engines has long been providing their 1/4" prop shaft engines with standard 1/4-28 threads and nuts, making it easy to locate a replacement nut. Sadly, they've backed up on the .40LA and reverted to metric threads. And the prop nut is a tiny little 10 mm item, too, making it all too easy to round off the corners unless you use a socket wrench when tightening.

The O.S. .40LA comes with a nifty remote high-speed mixture adjustment (needle). Instead of being located directly on the carburetor, it has been moved back, further from the spinning prop, making this essential adjustment safer and sometimes easier to perform. The mounting bracket, however, is an integral part of the engine's rear cover, and is thusly non-adjustable. If the needle interferes with anything in or around the engine compartment of your model, it may be necessary to modify your model to suit.

In keeping with its low price, I assume, the .40LA is equipped with an air bleed carb instead of twin needles. Not surprisingly, then, this is not a reliable hand starter, and even with considerable running time accumulated, I found it very difficult to start this engine by hand. In fact, even with my trusty electric starter, the .40LA sometimes takes a second or two to light up and starting making noise.

Noise? Did I say noise? That may be an inappropriate term for this engine! The .40LA and #E3030 O.S. muffler make for an unbelievably quiet combination! Even at full power with the highest RPM prop tested, we were unable to measure 90 dB(A) (measured from three meters, or ten feet, from the muffler side of the engine). Even when twisting a little 9x6 prop at over 12,000 RPM, this engine knocked out a quiet 88.5 dB(A) maximum reading! This is one quiet engine! Sorry, 4C fans, but you're not likely to find a .40/50 size 4C engine less offensive than that! It's remarkable!

Once again, I'm happy to see O.S. Engines continue with their policy of having most of their engines designed so that the muffler screws thread into the muffler instead of the engine. It doesn't take a terrible crash to damage a muffler and rip those screws right out of their threaded holes. If the muffler screws thread into the engine, though, the engine crankcase is often ruined as well as the muffler.

The O.S. #E3030 muffler also has a removable baffle for those modelers who want a tad more power, at the expense of more noise. Also, the outlet of the muffler can be rotated to direct the exhaust gases and goop away from your model.

The instructions provided with the O.S. .40LA are just excellent. It includes specifications, prop, fuel, and glow plug recommendations, troubleshooting steps, an exploded view drawing, parts numbers, and more. Good job, O.S.!

Once running, this engine is easy to adjust, with its rear mounted high-speed mixture adjustment, and wide adjustment range. If adjusted a little too lean, the engine begins to sag, but it doesn't immediately fall flat on its face and die. The engine runs smoothly (assuming a balanced prop and spinner, of course), and it didn't leak exhaust residue anywhere, and no fuel leaks were spotted at the front end. Even after all the break-in running and prop testing, the engine still looks clean and shiny as new. The provided instructions do warn, however, that the blue finish can be marred if using strong cleaners. With this in mind, I just wiped the engine down with a clean paper towel, which left it looking good as new.

Even though the O.S. .40LA does not start easily by hand, it does have nice idle characteristics. We do not expect such a low cost and very quiet engine to be a real powerhouse, and the O.S. .40LA did not surprise us. It definitely falls into the low power range for 2C .40's, but for many modelers, its positive features will more than outweigh its modest but acceptable performance.

Reprinted with permission.
October 1997 R/C Report
Editor: Gordon Banks