Builders,
These procedures come from extensive testing last year. If you want to know what my recommendations are based on, look at the testing in the two stories below. They are well worth reviewing, even if you are not a potential Stromberg user, because the stories show the extent of the practical evaluation I do to make Corvair powered aviation safer. Note that I have never sold Stromberg, nor ever made a dime off them, they are just a common carb that my builders have used, and as such, I take it as my responsibility to assist builders in doing so at lower risk. You would think every commercial person in Experimental aviation feels that way, but they don’t. I don’t need praise not a medal for doing this, its just the stuff that everyone should do.
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Stromberg Shootout, Pt #2 (2019)
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Shootout at the Stromberg corral (2019)
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There are two outfits in the US which are well known to work on these carbs. One of them touts being the best in the world, and claims understanding no one else has. I spoke with them directly on the phone where they claimed to have built carbs to the Continental C-85-14F standard and they ran perfectly on a number of Corvairs. But, when pressed, they could not name a single customer, nor provide a picture, and admitted to no direct testing. As a pure test, Dan Sheradin and I set a carb up to the exact C-85-14F standard, and it hardly ran at all. Keep this in mind when people inevitably push back against my recommendations here: They will not be able to produce a single photo like the one below, of actual testing. Your money, your plane, your life, your choice of who to listen to.
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Here is a link to a you tube video where I explain how and why procedures have changed:
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Above, Dan works on setting the float height, which is one of several mixture adjustments
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Categories of Stromberg users:
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A) You have a Stromberg on your Corvair powered plane, it has flown more than 50 hours, and you are happy with it;
Suggested action = Keep going, operate your engine in accordance with the New – M.O.P. Manual, we have a long history of good service from Strombergs under these settings, and unless you alter the carb from its currently working settings and parts, logic suggests that it will continue to provide good service.
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B) You have a Stromberg, it is assembled to running condition or it has been overhauled, it may have flown, but it has not logged 50 hours of trouble free operation yet.
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Suggested action = I highly encourage you to contact me 904-806-8143 and discuss sending it in to me, where I can test it on a running corvair at high power settings with excellent air-fuel meters and verify its operation. If there is something wrong with it, many of these adjustments can quickly be made. There is a modest service fee for this, but it is small in comparison to the potential cost of operating an unverified carb.
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C) You are thinking about running a Stromberg, but you have not acquired one yet.
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Suggested action = I’m steering builders away from these carbs unless you come across an fantastic deal on a carb you have previously seen work. When we started, lots of these carbs were around, unmolested, for. $200. Fifteen years ago overhauls were $400 and done with good US made parts, and primers were $25 used and $69 new. Today the carbs are $350 needing a $600 rebuild, which can be done with parts of questionable origin and accuracy. The primers are $250. The “Experts” are changing $1,250 to overhaul a carb to a setting I know will not work on a Corvair. Under these circumstances, it makes a lot more sense for builders to use a new Rotec 34MM TBI for $850. it needs no primer. I am a dealer for these, and I run every single one before it goes out in the mail to a builder. Its just a much better value.
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For more info on carbs, look at this: Corvair Carb Reference page for 2020.
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To understand that carb testing has always been an integral part of my work, look at these links:
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Stromberg Carbs (2012)
Carburetor Reference page (2013)
Ongoing Carburetor testing. (2018)
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I would just like to express how much I appreciate how you are addressing the issue with these rebuilt carbs.
Fellow builders/ flyers, I have a rebuilt Stromberg that is not working properly. My original Stromberg as purchased on EBay about 8 years ago has worked perfectly on both my 2.7L and my 3.0L. I am flying that carb now. I recently purchased a spare Stromberg and had it rebuilt professionally expecting it to perform equally as well. This was not to be and even though he had nothing to do with the rebuild, William had graciously offered to test the carb on his own engine. In doing so, he had the same result as I did. He is currently working with me to find a solution. As he mentioned there have been other rebuilt carbs he has tested that are not functioning properly. The company who rebuilt my carb. have agreed to send another one to William so he can test it for me to verify whether it is working properly (or not).
Thank you William,
Jeff
Another priceless article; another priceless service. Although I have always expected to use an MA3-SPA ever since reading the first version of the Manual, I’m interested in the new FI. The fact you are willing to represent it says the most about it, but details are always important.
Your invitation to all to take advantage of your empirical knowledge, integrity, history, transparency, persistent enthusiasm to seek and share a better, safer, more reliable way to do things aeronautical every day, is a unique and outstanding gift. I know too much praise may give you the sense your existential foundation is being compromised. Oh, well. Even existentialists require affirmation.
My C-85-12 powered Cessna 140 has a Stromberg and I really wanted to replace it until I read the manual that originally came with it. The mixture control that most folks safety wire in the full rich position actually does work and you really can shut off the engine with it if you follow the manufacturer’s instructions.
Imagine that!