Around the Patch

Let go the carburetor.


News came as we were working on this, our annual engine directory issue, that Precision Airmotive, owner of the rights and tooling to the old Marvel-Schebler carburetor line, had ceased production because it could no longer obtain liability insurance. Understand that it was not because the company couldn’t afford the insurance; it couldn’t get it at any cost.

I saw this coming. In February 2006, I was checking out of an Arlington, Washington, hotel and saw then-president of Superior Air Parts, Tim Archer, in the lobby. He said he was in town “to see why it costs us as much to buy a carburetor as fuel injection.” The price of the simple, time-honored carburetor was shooting through the roof just as fuel injection was steady.

On the heels of Precisions news comes more, that Aero Accessories had purchased the line and would soon move it into the Tempest line. That’s great news for owners of carbureted engines because they’ll continue to have support. It remains to be seen if Tempest will be an original-equipment manufacturer for Continental and Lycoming; in particular, the O-200 has found a new following among LSA manufacturers, and it would be a shame to crunch that project under foot for want of a carburetor. (Jabiru and Rotax are in protected waters because they use Bing carburetors, themselves vastly more advanced than the very rudimentary Marvel device.)

But, for me, the bigger question is: Do we really need the carburetor for new installations? Does its supposed simplicity make up for its well-known shortcomings-poor mixture distribution, propensity for separations of the body and float bowl, tendency to form ice with nothing more than a sideways glance?

I don’t think so. In fact, this may be just the right trigger to force us to move on.

Without external influences, technology moves slowly. In cars and motorcycles, the carburetor has become the most minor of players, used only on the cheapest, lowest-performance bikes and on no new car that I can think of. Emissions and drivability issues pressed the carburetor aside-two things not a concern in aircraft. In my own motorcycle fleet, there remains one with carburetors, and getting the pair of em to work properly has always been a chore, a set of unhappy compromises. When the bike doesn’t get ridden, their tiny passages clog. My fuel-injected bike, thanks to an overlay fuel computer called a Power Commander, can be adjusted to near perfection, all through the USB port of a laptop computer. It can sit for weeks unaffected. Once a big fan of the carb on motorcycles for its more “natural” throttle response, Ive changed my tune. With patience, fuel injection can be tuned much better.

Fans of the carb say fuel injection is more complicated and suffers from hot-start issues. Bunk. When you add in the need for carb heat (with a heat muff, flapper door, cables) I think you end up about even with an injected setup, whose main complication is a more sophisticated fuel boost pump. Even though the 390 is available only injected, had I opted for a parallel-valve 360, it would have been injected, no discussion needed.

Hot starts? Its a matter of technique. I never had trouble with my old Bonanza, and after a summer trying various techniques, now have the Airflow Performance system in my IO-390-powered Sportsman knocked.

So, tears for the carburetors passing in aviation? Not from me.

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Marc Cook
Marc Cook is a veteran special-interest journalist who started as a staffer at AOPA Pilot in the late 1980s. Marc has built two airplanes, an Aero Designs Pulsar XP and a Glasair Aviation Sportsman, and now owns a 180-hp, steam-gauge-adjacent GlaStar based in western Oregon. Marc has 5000 hours spread over 200-plus types and four decades of flying.


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