Stromberg Shootout, Pt #2

Builders,

Dan and Tracy Sheradin arrived at 9pm Friday, after a long drive from NC. They were here to have some fun, and put a great effort into the Stromberg Shootout. Below are a few pictures of a long Saturday of testing which ran from 7:30am until midnight, with only a few short breaks.

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Tracy does a ‘Vanna White’ style presentation of our test carb line up. We ran them all today. That is a lot of carb, airbox, fuel line and throttle linkage changes on a hot motor in a single day.  We also paused to do compression tests and adjustments on my 3,000cc Corvair to insure we were running controlled tests.

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Above the engine running in front of my house with the first carb. The timing light is giving the RPM. Large round gauge is manifold pressure.

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Above, we ran two different kinds of plugs in the engine and tested fine valve adjustments to precision tune the engine. In the photo we are using a dynamic compression tester to measure trapping pressure in the cylinder, and comparing this with adjusting intake rockers.  It wasn’t the focus of the testing but it fit in with the series of tests.

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Above, this is what is inside a Stromberg. Hangar ‘experts’ claim these are “just a one barrel carb” but in reality they are a very well made, fully adjustable, robust carb. We disassembled three of the carbs to make internal adjustments.

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Above, Dan works on setting the float height, which is one of several mixture adjustments. the higher the fuel level in the bowl, it runs richer, This combined with main jets and air bleeds sets the air fuel mixture. A unique feature of the design is being able to set the float height on the table with the top of the carb off.

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After a full fay of testing, we looked at the results and chose to follow this recommendation from Bob Kachergius, “the Stromberg specialist.” We reset Terry Hand’s carb to this, and it will be the first one we run on Sunday. (Sunday update, I suspect we copied a number wrong, as this didn’t want to run well from 1,000-2,200 rpm. More later)

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Above, Dan got a kick out of looking at my decades old carb books, dating from my days at Embry Riddle. In looking through the book he saw that a scored 100% on the exam on MA-SPA  series carbs, but later found that I only scored 70 on a snap quiz on Strombergs…..he thought it explained a lot of why the day was taking a long time.

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Above, the engine running cleanly today

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More, after further tests..Wewjr

About William Wynne
I have been continuously building, testing and flying Corvair engines since 1989. Information, parts and components that we developed and tested are now flying on several hundred Corvair powered aircraft. I earned a Bachelor of Science in Professional Aeronautics and an A&P license from Embry-Riddle Aeronautical University, and have a proven 20 year track record of effectively teaching homebuilders how to create and fly their own Corvair powered planes. Much of this is chronicled at www.FlyCorvair.com and in more than 50 magazine articles.

5 Responses to Stromberg Shootout, Pt #2

  1. Dan Branstrom says:

    Ceteris paribus is a term often used in economics. It means, “with other conditions remaining the same.” It’s important in scientific testing, where a good test only includes one variable, to measure the effect of that variable.

    I applaud the effort to make sure that ceteris paribus is in effect. It makes sure that the results are as valid as possible.

  2. JEFF MOORES says:

    Good stuff William. Thank you

    Jeff

  3. Scott Romey says:

    Hey ww give my dad a call at dgsupply when you find the best setup for strombergs. We get them occasionally and overhaul them with what we think should work and get no feedback. I know that stromberg guy knows his stuff but he is not afraid to lay blame to others even if he is wrong. That’s just our experience. But other than that he is what I would call a specialist.

    • Scott, thanks for the letter. I think you are right, engine specific first had testing is very educational compared to knowledge which is generally true about Strombergs. I appreciate that you and your Dad have always had a positive outlook on fine tuning our application.

      Although I have a lot of time in Graces Taylorcraft with its Stromberg, I have not personally owned a Corvair powered plane with a Stromberg in more than 15 years, and all of our engine test runs have been with a MA-3. The testing was a very in-depth refresher on the carb. Dan and Tracy were a huge help. We actually changed carbs about 15 times, pulling them off to change small variables.

      Bob was certain that the Jetting for the C-90-14F was going to work best, and I’m sure it does on a C-90, but out tests said otherwise, by a wide margin, it was an educated guess, but testing is the only measure which counts.

      Please tell your Dad I’ll call him and give him a full rundown this week.

  4. Tracy says:

    Thank you William for allowing us to come and assist with this process. As a wife and future passenger in an aircraft with a Stromberg carb, I am much more at ease knowing that it will run properly as expected. Thank you for caring about an aspect of an airplane in which you have no control regarding quality of workmanship. That is why we chose a Corvair as our engine of choice.

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