Ma3-SPA carb orientation

Builders:

A KR-2 Builder started a little internet tempest by asking a discussion group what was the ‘right’ way for his MA3 carb to face on his plane. This came complete with the insinuation that I advise people to mount them ‘backwards’, and speculative responses about it never working, terrible risk, etc. All the great answers you would expect asking a question on a discussion group where most of the people have mystery email names and very few answers come from people who have ever flown the combination.

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Above is the MA3, freshly overhauled by D&G Supply in Niles MI, (269)-684-4440. This is the FAA fuel system repair station that is run by Russ Romey. We have been sending builders there for 12 years. He is an excellent source of rebuilt MA3’s and Stromberg NAS-3s. You can read the story here: MA3-spa carb pictures, Wagabond notes. I have an entire section of my website devoted to carbs here: Carburetor Reference page. It has  been there for two an a half years. Because I have good tracking on my page, I can tell that not one single person read it this last week, because it is much more fun to ask internet strangers for answers than do a little reading.

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The originator of the question, later sent me a note asking the same question, never mentioning that he had previously asked it on the open net. His question included a picture of his carb linkage spaced out by an An3 bolt with 2″ of washers on it, asking if it was OK to do this. He also mentioned getting advice on this from his local expert who was qualified because he was an A & P and a Tech Councilor.

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I will try to keep this short: If you want to know something about your Corvair, ask Myself or Dan Weseman  first, not after you go to the internet and imply I tell people to do things wrong. Second, I have used the term ‘Local Expert’ in a negative sense in countless stories like this: “Local Expert” convinces builder to use cast pistons. I don’t care if your ‘expert’ has an A&P or is a tech councilor. Real A&P’s know never to give advice on any model of plane they haven’t been trained on…Realize also that about 100 experimentals crashed on their first flight last year, and I am going to say that Tech Councilors looked at 80% of them and never spotted the item that caused the issue. (neither did the FAA) And last, if you need to kill yourself, putting the throttle linkage on 2″ of washers on an airframe with poor survivability, will do the job. (Before sending hate mail please read: Steel tube fuselages, “Safe” planes and 250mph accidents)   But I kindly ask that those bent on self destruction please use another tool besides a Corvair powered plane, as I already know plenty of people in the FAA and NTSB, Read Comments on aircraft accidents.

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FACTS:

The carb we use is a 10-4894 from an O-200 in a Cessna 150.

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In that plane, the data tag faces the prop. It works fine.

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In tricycle geared Zenith aircraft, we put the carb on with the data tag facing the firewall for clearance reasons. There are more than 100 planes flying just like this, It works fine, and any internet joker who says it does not has no credibility. We have been flying them that way for more than a decade: 12 years of Zenith’s powered by FlyCorvair Conversions.. It works fine.

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On planes were nose gear clearance is not an issue, We install the carb with the data tag facing the prop. We have done this on many airframes, including our 601XL. It works fine.

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I have also made a one of a kind installation where the carb was sideways. It worked fine.

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When I put a linkage on a carb arm, It either has a fork end, or an AN3 spherical rod end right next to the arm, with an area washer outboard of it, and the bolt always has a cotter pin in it. If done this way it works fine.

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If you want to kill yourself, stacking 2″ of an 3 washers on a skinny bolt and putting the throttle linkage on the outboard end of this will do the job It works fine.*

*Just imagine the new pilot on his first flight, suddenly aware on final that his plane doesn’t glide well at the speed he is used to approaching, is startled, and jams the throttle in for power, except the long skinny bolt bends, and the throttle stays shut, and his glide path leads to a point 100 feet short of the threshold. His nose gear breaks off in the soft dirt, the bottom cowl digs in,  breaks the 5/8″ x 5/8″ wood  longerons, fractures the fiberglass header tank, and his IFR panel wiring provides the ignition source.  Right after they put out the fire, The A&P / Tech Councilor will say “It was that God Dammed Corvair motor that killed him, I told him to get an O-200”. 

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The 20 minutes it took to write this was probably a waste of my life.

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-ww.