“Corvair Fast Burn” Ignition timing settings

Builders:

The sun is just setting here, but 15 minutes ago we had pretty close to standard atmospheric conditions here, and it was an excellent time for an important test I wanted done with a minimal correction factor. I was testing “Corvair Fast Burn” ignition timing settings.

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OK, here is the concept: If you…….

A) Have a tight quench area in the head, as SPA machines them,

B) Have the correct spark plug (the recommended Denso’s, nothing else)

C) Have the carb set for the Correct air/fuel ratio at wide open throttle

The engine can be set to make 98% of it’s potential power output, with greatly reduced ignition advance, giving it a very, very wide margin of safety against detonation.  Even with reduced octane fuels.

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Above, the digital Air-Fuel meter from this story:Shootout at the Stromberg corral in action. When I say the carb must be spot on for the setting to work, It means you have to have the correct model carb, jetting as we recommend, not something that kind of looks like it.  If you have a carb running lean, it will be very prone to detonation, no matter what other factors are at play.  When you read that 115/145 octane fuel was used on the last of the piston powered airliners and bombers, the dual rating of the fuel is its comparative Octane rating for running lean (the first number) and rich (the second number) The Octane of the fuel you are using means nothing if it is running lean.

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OK, the results. I use the panel of the run stand as a note pad, because it is easier than writing on a clip board in a 125mph wind. The first number is the total timing advance, the second number is the full static rpm of my test prop.

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LooK:

35 degrees (never use this) is 3360 rpm. This worked because it was a cool day, and I have everything set perfectly, on a hot day, sustained power at this setting would be on the ragged limit of detonation.

Now look at 26 Degrees: It turned 3340 rpm. That is 98% of the power output, but with 9 less degrees of ignition advance.  Note this set of tests was conducted with 90 octane gas. I will very shortly have a more formal recommendation to setting the timing on 3.0 and 3.3 Corvairs, but as a starting point, there is no need to use more than 26 degrees. The power output difference is hardly measurable, but the detonation resistance is radically increased.

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Wew.jr.

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Thought for the Day: What Girl Scout Cookies can teach you about Homebuilding.

Builders,

It’s that season again, when little green and brown clad urchins barricade supermarket exits and demand $4 and your will power before they let you pass. I’m against negotiating with terrorists, but I do have a particular problem with Thin Mints and Tag-alongs that makes me a poor negotiator on this subject.

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Wouldn’t it be great if Girl Scout Cookies were good for you? What if they had no calories, were completely balanced nutrition, and you dentist said things like “Your teeth are so white, I see you have been keeping up on your Thin Mints”.  A pleasant fantasy, but everyone understands it isn’t vaguely associated with reality.

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Above;  My 1939 copy of “Your Wings” by Assen Jordanoff, and proof I have no will power around Girl Scout Cookies.  The book is a classic from an era where knowing your stuff was central to being an aviator.  It still is, but most people would rather be wowed by interiors, glass cockpits and paint jobs. They pay little attention to the fundamentals of flying. This $20 used book has more human reward and satisfaction in it than any $2,000 interior ever will. 

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OK, so everyone understands how idiotic it would be if I tried to tell people a diet made of 100% cookies was good for you, why don’t the equivalent fantasies in aviation bring the same condemnation?

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When people say:

“I want to have a totally reliable homebuilt, that never gives me any issues, and I want to safely fly my family around the country in it. I want it done in one year, and I want it to look great.………But I’m unwilling to spend any money on the engine, I don’t comply with AD’s and Service letters because they can’t make me, I never read directions, I only listen to people who tell me what I want to hear, I paid $2,000 for an interior but will not spend a penny on transition training, I can’t tell you the Va of any plane I have ever flown, and I bought my kit off barnstormers because it was 25% cheaper than a new one, and I’m just going to ignore all the ‘snowman’ holes drilled in the spar with no edge distance because I’m not going to fly aerobatics and planes are overbuilt. “

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If you catch anyone in homebuilding saying any part of the above statement, or any variation on it, please treat them as if they are telling you Girl Scout Cookies are pure nutrition.  Well built planes are made of reading, learning, understanding and craftsmanship. Their successful operation is made of training, understanding and good judgment. There are no short cuts to this, there is no magic. 

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There is a certain kind of person who doesnt like hearing what I just said. They like thinking they can game the system, or in modern parlance, “hack” it to allow them some personal short cut. They think paying your dues, learning and real training is for average people who can’t figure out the angles.  After 30 years in homebuilding, I can tell you these are the first people to quit…if they are lucky. In the rare chance they finish, sooner or later, reality and physics show up with a bill that can’t be paid.

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Wewjr

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Dual 50K volt test ignition

Builders,

Not all tests are directly aimed at making a product next month, some are pure R&D to test ideas which may or may not be integrated into later products. Either way, the understanding which comes from afternoons like this is part of what makes my experience valuable to traditional homebuilders.

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Above: On Sunday I let this test ignition run on my 1947 sun distributor machine for several hours. Get a look at that spark, it is arcing over a 3/4″ air gap. It performed flawlessly, but is it something useful? In spite of working great for hours, it would still have to pass three critical tests: Power consumption, elevated heat tolerance and low voltage ability.  My current E/P and E/P-X ignitions do, and they do it affordably.  Looking at a system like the one above, it has advantages, but they come with questions and a different price tag. These are the the things you consider while this hums away in the shop for several hours.

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The Details:

Body: Corvair dual bushing

Cap adaptor: Ford V-6

Pickups : Chrysler slant 6

Reluctor: Hand made

Module A : Chevy V-6

Module B: 1981 Pontiac 301 turbo.

Coil : Echlin 1990s GM E style, ultra low resistance.

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The wiring is spread out a lot to make it more accessible for testing, it facilitates putting the heat gun and thermal camera on individual elements to see how the perform under duress.  Yes, Vice grips have a place in the world of tests and evaluations.

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wewjr

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‘STOL Bowl’ availability starts tomorrow.

Builders,

A long awaited image below; that is six of my new “STOL Bowl” nose bowls next to my truck outside the loading bay at the SPA factory. These are now boxed up and ready for shipment.  We are now at a regular production rate of 5 per week coming out of the new mold.  We will update the products page in a day with pricing to reflect this availability.

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Above, after many months of development, we now have regular production. This part, #4201-B, will be the new “Standard” part, and it supersedes the #4201 for all applications. There is no appreciable drag penalty on Corvair planes flying below 140mph, and the “B” model does have a significant cooling advantage. Starting tomorrow, the products page will reflect these status changes to 4201 and 4201-B, and we will have the new bowls available at an introductory price.

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More news shortly.

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William.

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3,000cc Corvair, Video #2

Builders,

OK, now you know I’m not kidding about being a knuckle dragging troglodyte around computers. Good thing I have the charm of David Niven, the wardrobe of Sinatra and the dance floor skills of Fred Astair .

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Video #2, 3,000cc Corvair in my yard today, idling smoothly at 700rpm.

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Video of 3,000cc Corvair

Builders,

I know engines but not IT stuff, this is a test to see if I can get a video of today’s 3,000cc Corvair run to show up.

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Wewjr.

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3.0L Corvair for Sale, running on video.

Builders,

14 days ago I posted this story about a new Corvair for sale: Outstanding Deal on New 3.0L Corvair..  We had a lot of nice comments, a number of interested builders, but as of today, it’s still in my hangar. If your plans for flying this season need something to accelerate them, get a good look, there will not be another deal this good in 2019.

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Above, the engine running at 4:30 pm today in front of my hangar.  If you are interested, I will change the valve covers to any color you like, or reconfigure the oil system to suit any standard installation.

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Above, 30 seconds of running at 700 rpm. This is running on the silver carb from the previous story.

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Above, 15 seconds of running at 2,000 rpm.

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Above, a detail look at the 2400L starter system, the SPA Gen II billet 5th bearing and the A Gold hub. The engine is nicely detailed.

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A look from above, a view that highlights the Corvair’s simplicity. This is back in the hangar after the run. Motor is very clean.

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If you are interested in the deal, call or text me personally at 904-806-8143.

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William.

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(Ps, Dan Glaze, I was going to make that “Any Colour you like.”)