16 Flying Corvair powered Zenith 601/ 650s


One of the most read stories I have put here is this one: Pietenpol review in pictures, 15 more Corvair powered Piets. Over the last months, it has had several thousand page reads. While I am working on a reference page for 601/650s, I thought I might put together a quick review in pictures of some 601’s and 650s.

Over the years we have had more than 70 of them fly, but here is a quick look at 20% of them. I selected these because they I wanted to show how many people use them for trips to places far away.  I have had people who should know better say to me “you need a Bonanza or a 210 to fly cross country” Claims like that are just ridiculous. First, a 601/650 gets more MPG than those planes, and second I would gladly fly a 601/650 with their gentle approach and touch down speeds into many small strips that you would be a fool to try in many traditional GA “Cross Country” planes. 

Frankly, If I am going to fly around the country to enjoy myself, I am not myopically focused on is seeing how quick I can get the experience over with.  The 601/650 has a very useful combination of reasonable speed, small strip capability,  good range and both baggage volume and weight capability.  This gives their builders access to a lot of good adventures, as evidenced by many of the photos below.


Above, Pat and Mary Hoyt’s 601XL (with 650 canopy) at Brodhead WI, 2013.  The airport has clear approaches, but is a fairly short grass strip. They also flew to Oshkosh and the Zenith open house in MO this year. 2,700cc Corvair power.

Above, Brodhead 2012, Ron Lendon of MI with his 601XLB, plans built, 2,850cc Corvair. Ron also flew to Oshkosh, and this year flew to Sun n Fun in FL and to CC#25.

Above, Sun n Fun 2006, in the Zenith booth. The above photo shows Phil Maxson standing by his 601XLB along with Gus Warren. Phil’s plane has flown back to FL many times and to several Corvair Colleges including #10 and #24. Corvairs and Zeniths are a long proven combination. 2,700cc Corvair power.

Above, the Zenith booth at Oshkosh 2007.  Dr. Gary Ray of MI and his 2,700cc 601XLB. He has also flown the plane to CC#20 and to the 2011 Zenith Open house in MO.


Above, the Zenith booth at Sun n Fun 2013. Lynn Dingfelder’s  601XLB with 2,700cc Corvair from PA. The plane has also flown to Corvair Colleges #20 and #25.

Above, Oshkosh 2011. In the above photo, Woody Harris’ 2850cc Zenith 601XLB. This plane is based in CA but has flown all the way to NC and back, and has been the full length of the west coast. I am pretty sure it has flown in 25 states, and that is mostly the big ones out west. Engine is a 2,850cc Corvair. Plane has 340 hours on it.

Above, Charles Leonard’s 601XLB in Punta Gorda FL. Engine is a 2,700cc Corvair. Plane finished and flying since 2009.

Above, Shayne & Phyllis McDaniel with their 650 at the 2012 Zenith open house. This aircraft was seen by thousands of builders at its Oshkosh debut, it displays outstanding workmanship. It was the first amateur built 650 on the FAA registry.  Engine is a 2,700cc Corvair. 

Shayne & 601 N809SP

Shayne stands in front of their second Corvair powered Zenith, a 601XLB with another 2,700cc Corvair. They are both skilled pilots and they like having ‘His and Her’s ‘ Zenith’s. It is a sure sign that you line a combination when you build a second one.

Above is Andy Elliott’s 601 XL tailwheel aircraft, now converted to 3,000cc Corvair from an older 3,100 Corvair. The plane is from AZ, and it has more than 500 hours on it. It has been all over the West, and flown as far east as Oshkosh.

Above, L-R, Michael Heintz, Rick Lindstrom and myself at Quality Sport Planes in CA. Award is ‘best engine’ from Copper State AZ show. Michael was local host for Corvair Colleges #10 and #11, Rick was local host for #13 and #18. Rick’s 2,700cc XL was built in our hangar in FL, and has flown it Southern CA and all the way up to Arlington WA, covering 3 corners of the lower 48.

Above, Gary Thomas’s 2,700cc 601XLB at Corvair College #16 in SC. Gary is formerly of Florida and now from North Carolina. The plane was also flown to CC#21.

Above, photo taken at CC#16 in SC. Scott Thatcher’s 601 XL. This was the first College to which Scott flew. He has also flown the plane between FL and NC, and flown it back to CC#21.

Above, I stand outside at the 2009 Zenith Open House with David Coberly from AR,  and his 601 XL. First time I had seen the plane or met the man. Outstanding craftsmanship. 

Above, Dave Gardiea and his 650. Aircraft has flown to Oshkosh and the 2012 Zenith open house. Engine is a 2,700cc Corvair.



Above, Louis Leung of MA and his 601XLB at Oshkosh 2013. Engine is a 2,700cc Corvair.

Airframe specific refrence pages.


Yesterday’s Zenith 750 reference post is the first of a half dozen I am going to do over the next few weeks.  The others will probably include the 601/650, Pietenpols, Cleanexes and KR’s. I am planning on utilizing much of the same format in each of these. This may seem redundant, but bear with me on this, I believe that it will prove to be a good use of writing time.

Here is the logic: The way we have presented the information up to this point is assuming that the person has already selected the Corvair and is at least some what familiar with our work and the Corvair movement. If you are reading this, that may be a good description of your arrival as a Corvair builder. However, I think that most people interested in building an experimental aircraft first select the airframe that interests them, and only later try to find a matching power plant.

I have concluded that many people with a specific airframe already in mind consider a Corvair, but on a first visit to our websites, have a hard time getting a complete picture of how the Corvair can serve on their chosen airframe. I am well aware that finding things, particularly on Flycorvair.com can be difficult.. Thus I have begin to develop the idea of the airframe specific reference page.

Now, Picture a guy who has just started his Zenith 750 project asking on a Zenith discussion group for information about engines. Any builder of ours can just simply reference the one link, where the new builder can read the information at any depth he likes.  Same goes for people who send us a direct email saying they are considering a 750.  It should also turn up on searches. In any case, it is no more difficult than just sending a new guy to the main page and suggesting he start there, but it should do a much better job of giving the interested person a more accurate overview of the possibilities of the Corvair.

It has the other advantage of being easier to update with more information and newly completed planes and fresh stories. This way links in older archives are tied to current information not just older posts. If you already know your way around the Corvair , have been to a college and the reasons for our approach make sense to you, all of this may seem superfluous, but it just says you are more motivated and better informed than most builders. 

Today we get mail from and meet a lot of people at airshows that have heard about Corvairs, but are missing fundamental points like the fact you can build the engine yourself , that new parts are made, that we make installation components and we hold the Colleges.  Standing at my booth at Oshkosh, the 20th time I have been there, with eight motor mounts in the tent with signs on them and having at least 5 people a day say to me “I read your website, and I like the Corvair for my plane, but I don’t know where I can get a motor mount for my Zenith 601” is a bit frustrating.  I could get cranky about it or I can do something productive that re arranges the info that we already have to make it more accessible to people at first pass.

The same ‘reference page’ idea can work for topics that current builders are interested in also. The 3,000cc development story: 3,000 vs 3,100 cc Corvair engines. , was very popular, and it was essentially organized the same way, and when we have another good story on 3,000cc engines, I can just go back to the first story and insert the link to keep it up to date. I am open to hear any feedback on these ideas or hear of subjects for additional reference pages.-ww

Zenith 750 / Corvair reference page, October 2013


Here is a single location page that has a great number of links to information specific to the Zenith 750 / William Wynne-Corvair Combination.  It is a particularly good match, we have a number of different ways to approach it that serve the needs of many different builders, and it is a success story that builds on our 10 year history of working with Zenith builders, starting with our own personal 601XL in 2003. Since then we have assisted more than 80 builders to complete and fly their Corvair powered Zeniths. In the coming years these will be accompanied by an ever increasing number of 750’s.

If you already are working on your Corvair, this page will have information you have seen already on our websites, but I have included it so that this page can function as a ‘stand alone’ guide for 750 builders who have just heard about our work with the Corvair. Our approach to serving builders is different than typical businesses geared only to sell things to consumers. Our goal is to assist you on your path to becoming a more skilled aviator. The products we sell support this, but simply getting you to buy things is not what I am in aviation to accomplish. If you would like to start with a simple three page spec sheet on the engine, read this link first: Basic Corvair information

This page is broken into the following sections:

1) Introduction

2) Engine and build options

3) installation components

4) Support for builders

5) Flying 750’s

6) Builders in process

7) 750 flight data and safety notes

8) who is WW?

9) Comments on dangerous trash.

At the end of each section there are links to supporting stories that have expanded information on concepts discussed in the section. Take your time and study it carefully.

I will be glad to answer further questions just email WilliamTCA@aol.com or call 904-529-0006. You can also check our two websites, http://flycorvair.net/ , http://flycorvair.com/ . The first is our ‘newspaper’ the second is our ‘library’ and ‘store.’ The links below are stories that already appear on these two sites, they are just arranged here to support this introduction to Corvair power for 750 builders.


Above, the flying 2850cc Zenith 750 built by Gary Burdett of Illinois.  It has our full complement of Zenith installation components and one of our production engines.


1) Introduction:

The Corvair has been flying since 1960, and I have been working with them as flight engines since 1989. It is a story of careful development and testing, a slow evolution to the engines we have today. It is ‘old and proven’ rather than ‘new and exciting.’  If that approach appeals to you, read on. There is a lot of material here, and it isn’t something you are going to absorb in one quick scan. Frankly, your engine selection deserves careful consideration, and it isn’t the kind of decision you should make based on a 4 page sales brochure.

Corvairs have proven themselves to serve a very broad variety of builders. Many alternative engine options for the Zenith are offered only as a “buy it in a box” import, more of an appliance than a machine, with little or no consideration of the builders, skills goals, needs, budget or time line. The Corvair has options to address these valid considerations, because your power plant should conform to you, not the other way around.

This said, Corvairs are not for everyone.  In the 25 years I have been in the EAA and working with builders, the Corvair has always been very popular with ‘traditional homebuilders’, the people who have come to experimental aviation to discover how much they can learn, understand and master.  The expansion of the EAA has brought more of these builders, but it has also brought a great number of people incapable of distinguishing between mastery of an aircraft or an engine and just merely being its buyer and owner.  People who’s consumer mentality and short attention spans are better suited to toy ownership than mastery of skills and tools in aviation. Corvairs, and perhaps experimental aviation, are a poor match for such people. Many salesmen in our field will gladly sell anything to anyone with green money. I am an aviator, not a salesman, and the gravity of the subject requires more frank discussion and ethics than many salesmen bring to the table.

If you came to experimental aviation to find out how much you can master, not how little, then you are among the aviators who follow Lindbergh’s timeless 1927 quote: “Science, freedom, beauty, adventure: what more could you ask of life? Aviation combined all the elements I loved.”  Even if you are brand new to aviation, I am glad to work with you. I have a long history of working with builders of all skill levels. We have a number of successful builders out flying their Zeniths who are the masters of both their airframes and engines, who had never changed the oil in a car before building their plane.  If you got into experimental aviation just to buy stuff, then any salesman will do just fine for you. If you got into experimental aviation to learn, develop your own skills and craftsmanship and make things with your own hands, then who you work with really matters. You can’t become and old school homebuilder / motor head by buying things from salesmen. They have nothing to teach you. What you will do in experimental aviation is not limited by what you already know. It is only limited by what you are willing to learn, and selecting experienced people to learn from.  If you are here to learn, I am here to teach. It is that simple.



a) – Complete Lindbergh quote is here: The Quote, 1927, C.A.L.

b) – Explanation of machines vs appliances : Machines vs Appliances Part #2

c) – Story of real engines vs ‘ideal’ ones: Unicorns vs Ponies.

d) – An example of our ling standing working relationship with Zenith: Friday out of shop until 4pm.

e) – A direct explanation of what makes my work different than typical LLC’s : 2011 Outlook & Philosophy

f) – A moving statement of philosophy: Sterling Hayden – Philosophy


Above, the 3,000 cc Corvair, configured for a Zenith 750. An inherently simple engine, It’s opposed six configuration makes it the smoothest of available power plants. It has outstanding cooling because GM put a tremendous amount of cooling fins on it and  gave it a factory CHT redline of 575F. All of our engine parts are made in the United States.


2) Engine and build options:


If you are new to Corvairs, lets quickly cover some ground: General  Motors made 1.8 million Corvairs. brand new parts, including billet cranks, forged pistons, valves bearings,  virtually every single part inside is currently made and readily available, and will remain so. Rebuildable Corvair engines are plentiful, and much easier to find that Lycomings or Continentals. We have been working with Corvairs for 25 years, and there is no shortage of core engines or parts. If you doubt this for a second, Google “Corvair engine parts.”

The Corvair makes an outstanding aircraft engine because it is a simple, compact, direct drive, horizontally opposed six cylinder, air cooled engine. It is robust, and ‘flat rated ‘ from it’s automotive output. The engine runs equally well on automotive fuel and 100LL, and it does not care about ethanol. In its 53 year flight history, more than 500 experimental aircraft have flown on Corvair power.

The engine can be built in three dispacements with three respective power outputs. They are 2,700cc / 100HP, 2,850cc / 110HP and 3,000cc / 120HP. The two smaller displacements weigh 230 pounds, the larger actually weighs 8 pounds less because it uses lighter cylinders. All engines are completely rebuilt from very high quality parts before flight. They are not just removed from cars. The parts we use are specifically selected to convert the engine for the rigors of flight use. Forged pistons, Inconel valves, chrome rings, ARP rod bolts and many other components are upgraded in the rebuild.

To absorb the propeller and flight loads a “5th bearing” is added. It is a billet housing with a very large bearing from a V-8, bolted on the end of the case.The ignition is redundant and utilizes two 40,000 volt systems, one driven by digital electronics the size of a match book, the other by a traditional set of points. The engine is direct drive, it has no complex reduction unit. It makes good thrust because it has more than twice the cubic inches of a Rotax 912. All of the systems on the engine are intentionally patterned after those on Lycomings and Continentals, because they are the  model of success in proven aircraft power plants. People who do not acknowledge certified engines as excellent models of success are often just zealots.  To succeed in experimental aviation you need dispassionate information not emotional opinion.

One of the unique features of the Corvair is that it can be built at home, from our information and parts and a locally acquired rebuildable engine, or it can be purchased from us, test run with logs. 90% of current builders are building their own engine at home. Only 10% of the builders opt to have us build their engine. We have happy to serve both builders. In either case, Corvairs are the best match for builders who want to understand and be the master of their engine.

Because of the plans built vs production engine nature of the Corvair, there are large variations in how much builders budgets run. Below is a quick look at the differences. Keep in mind, these budgets are for first class, completely overhauled, zero timed engines with 5th bearings, starting, ignition and charging systems. We have clever builders who have built and flown engines for less than $3,000, but this not representative of main line builders. The numbers below are much better for Zenith builders to budget on.


2,700cc / 100HP typical homebuilders budget: $6,500- Same engine assembled and run from us $9,750

2,850cc / 110HP typical homebuilders budget: $7,500- Same engine assembled and run from us $10,750

3,000cc / 120HP typical homebuilders budget: $8,500- Same engine assembled and run from us $11,750


If you are attracted to the concept of building your own engine, but have not built motors before, Good.  About half of our builders have never built any kind of an engine before. Our main work is teaching people what we know and providing the parts to work with. Our system does not require anyone to be a machinist nor to have previous engine experience.

The procedure of building an engine in your shop follows this format:

1) Get a conversion manual and DVD’s from us, use them to find a rebuild able core engine locally. Disassemble this engine following the steps in the DVD.

2) Send the crank and heads to our approved facilities for rebuilding and modification. They come back ready to ‘bolt on.’ Other parts of the engine are cleaned and inspected. The parts to convert the engine are ordered from us, many of the standard rebuild parts like lifters and gaskets are available from local auto parts stores. We do not ‘middle man’ anything you can directly buy.

3) Assemble these parts according to the manual and DVDs. There is no machine work required, only basic tools are needed, and a few specialty tools like a torque wrench. Many builders attend our free Corvair Colleges and directly learn hands on skills. You can even bring your parts and assemble them under our supervision, and test run your engine on our equipment. College attendance is a plus, but not required. Our methods work without direct training; a good number of engines are built and flown each year by builders who have never met me in person.

4) The test run serves several purposes. We teach people to build one of  three specific models, and we teach them to use specific parts. Not only are these proven, but it also allows me to verify from a remote location that the engine was assembled correctly. A builder can report his static rpm, CHT, oil temp during the test run with his Warp Drive prop at the specified setting, and I can confirm the output and assembly of the engine without seeing it personally.

If you would like a sample of the information on working your way through the above four steps, get a look at this: Getting Started in 2013, part #1, Crankshaft process options.

I have broken down building a Corvair and installing it on your airframe into 42 “groups”. The previous link is about  ‘Group 1000’ the crankshaft. If you would like to look at every part that goes into a Corvair, along with the conversion parts we sell, look at Groups 1000 -3300 at this link to our catalog: http://www.flycorvair.com/products.html

All builders get started with a conversion manual. The first part of the above link is about manuals and DVD’s.  The direct link to the manual is: http://www.flycorvair.com/manual.html. almost all builders looking for a rebuild able engine also order the Disassembly  DVD, which covers core engine selection visually. The direct link to it is: http://www.flycorvair.com/videov.html We encourage everyone to get started with information, even if you are pretty sure you would like to purchase a production engine from us. If you eventually buy an engine from us, we directly reduce the price to rebate all the money you spent on manuals and DVD’s.



a) – Corvair Weight story: Corvair vs O-200…. weight comparison

b) –  Samples of our production engines:  2012 Corvair Engines For Sale: 100, 110 and 120 HP

c) – For an explanation of ‘flat rating’ and a 750 engine build : Shop perspective: Mastery or ?

d) – A story about engines running on our hangar Dyno: http://www.flycorvair.com/thrust.html

e) Engine of builder now working on 750 airframe: World’s Strongest 3,000cc Corvair, built by Greg Crouchley

f)  3,000cc engine we built for 750 builder Larry Hatfield: 3,000cc Engine Running

g) A story about the evolution on 120HP Corvairs: 3,000 vs 3,100 cc Corvair engines.


Headed to the 2012 Zenith open house, six of our powder coated 750 mounts. All of our mounts are welded in house, all of our parts are made in the United States.


3) Installation Components for the 750:

We provide every single part it takes to install a Corvair in your 750.  You can buy them one at a time, or all at once. Ninety percent of these parts are common to our Zenith 601/650 installation, which has been successfully flying for a decade. Only the mount, the diameter of the prop, and the size of the air inlets is different. Our Zenith installation manual detail how and why each of the installation components are installed on your airframe.

The installation does not require any modification to the airframe fuel system like most EFI engines do.  Being air cooled and carbureted, it is one of the easiest engines to install. Many companies that are good at selling things are poor at teaching things, like how to install their products. Teaching is the very cornerstone of my work, I am a skilled writer, we run Corvair Colleges, and we have a simple engine. All this adds up to a comparitively easy engine to install. There is no need to rush it, but I can do it working in one long day.

 Installation part numbers are Groups 3400 through 4300 in the second half of our numbering system. Get a look at this link: http://www.flycorvair.com/products.html From that list, you can see that the major installation parts for a 750 are: #3601(S) intake manifold, #3901(A) Stainless exhaust, #4002 spinner bulkhead, #4003 Warp Drive prop, #4101 baffle kit, #4102 nose bowl, #4103 cowl kit and a #4201(B) mount. The other smaller items listed are detail in our Zenith installation manual. All of the above parts have links to stories through the products page, but just for an overview of a single part, look at this link: Zenith 750/Cruiser Mounts. P/N 4201(B)

Many people new to building initially think that very economical engines like the Corvair must also be inexpensine to install. In reality, the cost of items like motor mounts and cowls are not affected by the cost of the engine they mount and house.  A mount for a $30K UL-350 and a $7K Corvair have about the same amount to tubing and welding time in them, and thus cost about the same. Most engines for Zeniths have installation kits that run from $4,000 to $6,000. The Corvair is near the bottom of this range, but the savings of using the Corvair is in the engine, not the cost of installing it. Builders can save a significant amount of money by fabricating many of the parts like #4103, but most people are near the finish line at that point and opt to buy it and save the time. Exact cost on the installation parts varies a bit, I will be glad to review it with builders after they study the installation manual.


a) – For an example of 74 years of aircraft welding talent: Zenith 601/650 Motor mounts, P/N 4201(A)

b) – To learn about the Stainless exhausts we make: Stainless Steel Exhaust Systems

c) – A 2008 look at how we developed the 750 installation on one of the first kits:


d) You tube video of an engine we built running on a 750 fuselage, 2009: http://www.youtube.com/watch?v=y_1ov0DAbe8&feature=plcp


An overhead photo of a CH-750 installation we did in 2009.


Above, 2004 at Oshkosh: Next to our personal Zenith N-1777W, I explain our dual ignition arrangement two executives from Falcon insurance, The EAA’s provider. To offer real support, an alternative engine provider must be an effective advocate for his builders on many fronts, including meeting the requirements of underwriters. Just being an engine guru is not nearly enough. Corvair engines that follow our design,  including to ones assembled by builders, are fully insurable at the lowest rates, right from the first flight, because they have an outstanding safety record. Having good effective hands on support is a critical element in this outstanding record.


4) Support for Builders:

Beyond the basic engine and installation components, we offer many forms of support to Zenith builders:


a) We have a very detailed Installation manual for all Zeniths: http://www.flycorvair.com/601im.html We also have a flight operations manual with specific test flight plans and procedures: http://www.flycorvair.com/ops09.html


 b) we hold 4 free hands on technical seminars called “Corvair Colleges” every year. This includes an annual College held in Mexico MO at the Zenith Factory timed to coincide with the factory open house in September. For an introduction to Colleges, read this link: http://www.flycorvair.com/cc21.html  An overview of upcoming colleges is at this link:  Upcoming events, Airshows and Colleges #26-28. If you would like to see video of a College, here is a link to Corvair College #17 http://www.youtube.com/watch?v=wfa85e3ibI4&playnext=1&list=PL1D40A102EC2A194D&feature=results_video


c) The “Zenvair” group is a separate on-line peer-to-peer discussion group just for Corvair/Zenith flyers to directly and freely share information and data with each other in a civilized productive format. The link is : ‘Zenvair’ Information board formed  This is very effectively moderated by Zenith/Corvair builder and flyer Phil Maxson.


d) Woody Harris, subject of this story:  Zenith 601XL-2,850cc, Woody Harris Is our west coast representative. Although we have held 5 Corvair Colleges in California, including 2 at Zeniths west coast facility Quality sport planes,  we only make one trip to the west per year. Woody covers all the shows and events from Arlington to Copper State when we can’t be there.


e) I am the last guy in aviation who still makes free house calls. Over the years I have made more than 400 in person visits builders projects. I travel extensively, and go out of my way to include builders workshops on these trips.  These stops and the colleges allow me to really understand the needs, strengths and dreams of rank and file builders that no one can read in email or at an airshow. for a sample, read this story: Corvair House Call, Range: 335 miles.


f)  By my continued advocacy and industry relations, Corvairs have full insurance, at the lowest rates, available from a number of sources. If you would like to find out more Contact Bob Mackey, VP of Falcon insurance, The EAA’s designated provider, seen on the left in the photo above.


g) Over the years, we have built a very tight knit community of like minded builders. If you read this story about fools at our county airport: A visit to the insane asylum, and it sounds like your airport, and if your local EAA chapter is devoid of homebuilders and filled with negative people, you will find the Corvair movement to be a powerful antidote. Many Corvair builders catch several colleges a year, there they find positive, outgoing, energetic builders, effectively making the Colleges their “local EAA chapter” We have worked very hard to attract outstanding people interested in accomplishing their goals. I  go out of my way to encourage new builders but I am intolerant of people who are compulsively negative. I am willing to be a cheerleader, but not a therapist.




Doug Stevenson’s 750, powered by a 3,000 cc Corvair engine in California. This was the first Corvair powered 750 to fly.


5) Examples of flying Corvair Powered Zenith 750s:

Doug Stevenson : Flying Zenith 750 w/3000cc Corvair, Doug Stevenson, California

Jeff Cochran: New “Zenvair-750″, Jeff Cochran, 2,850cc engine, N750ZV

Gary Burdett: Zenith 750 Flying on Corvair Power, Gary Burdett, Illinois

first story: Gary Burdett, 2,850cc Zenith 750, now flying. (engine selection)

Tom Siminski : Flying Zenith 750, Tom Siminski, 2700cc, PA.



Above, Coenraad Van Der Merwe at the controls of his 750 during the first run of the 2,700cc Corvair he built for it. In spite of a busy work and personal schedule, he completed the airframe and built his engine in 18 months. Electing to build your own engine need not significantly increase the length of your build.  In many cases, the vastly lower cost of this option compared to other engines allows the aircraft to be completed years earlier. Money, not time, is the limiting agent in most aircraft builds.


6) Examples of Builders working on this Combination:

Coenraad’s 2,700cc: Running Zenith 750, Coenraad Van Der Merwe, CA

Blain Schwartz’s 2,850cc: Zenith 750 Builder Blaine Schwartz video on you tube http://www.youtube.com/watch?v=B4HwntCo2-I

Rodger Grable’s 2,850cc Corvair College #23 – 2850cc Engine, Roger Grable, CH-750 Builder



7) Operational Data for this combination:

If you would like to read a story about detailed flight data collection on a 2,850cc 750, check out this link: CHT part #5, flight data from Zenith 750 . It is an example of the type of information exchanged on our ‘Zenvair’ group.  If you are attracted to a builders group that is made of intelligent thinking people, you will fit right in with Corvair builders.

If you would like a single example to effectively demonstrate that I am an aviator not a salesman, it is the type of data that I discuss with builders. No salesmen will acknowledge accidents nor difficulties that involved their products, even circumstantially.

Conversely, I am here to teach people what they need to know. I have a long history of writing about subjects that salesmen wouldn’t touch with a 10 foot pole. I write about accidents and friends I have lost, honest mistakes people made and things you can learn from them.  Just about everything know in aviation cost someone dearly to learn. If you are unwilling to talk about these things in plain language, people are doomed to repeat them.

For an example of  plain speaking, I conducted an in person investigation of an accident on Doug Stevenson’s 750. It had an off airport landing on it’s third flight, and was damaged. It was caused by fuel exhaustion. You can read the whole story at this link: http://www.flycorvair.com/stevenson.html . Doug made a simple mistake., but he was man enough to admit it, and he wanted others to learn from it. As the leader of the Corvair movement I long ago set the ethic that we don’t demonize men for honest mistakes, we work with them to investigate and teach others. Doug repaired the airframe and we tore the engine down and internally inspected it. His aircraft is back flying and a proven performer now. As you read the report, keep in mind that I am a graduate of the same Embry Riddle degree program that most NTSB accident investigators. The data I collected, including the video, was taken into the official report.



Above, A photo taken at Sun n Fun 2006. My wife Grace Ellen and myself, in front of the first Corvair powered Zenith, our own N-1777W. The plane was the first XL model with conventional gear.  Grace is a skilled pilot in her own right. She has been a pilot longer than I have, holds more advanced ratings and owns two aircraft. As a point of ethics, we do not promote, advocate nor sell things we have not personally flown behind.


8) Who is William Wynne?

Modern consumer sales logic dictates that that business should ‘de-personalize’ themselves so consumers find nothing objectionable about the provider while they are spending money.  That model may work elsewhere, and even have advocates experimental aviation, but I don’t buy it.  I contend that Aviation is a different arena, and who you are dealing with, and their ethics, experience and perspective matters.

Building a plane or an engine is a marriage of sorts between the builder and his airframe or engine company. I believe that it is best if everyone goes into it well informed with their eyes wide open. I am always surprised how few people even Google the name of a person they are thinking of working with. You don’t need to see eye to eye with them on every point nor even love them, but the relationship must absolutely have trust and respect operating in both directions. In 25 years I have seen many builders try to justify buying a product from a provider they didn’t really trust. It never works out. It doesn’t matter how good it looks, what it costs or how great it is supposed to work, if it is from a bad guy, it isn’t worth buying.

I could write a quick paragraph about how I am a pilot, a 22 year A&P mechanic, and that I hold both an AS degree in Maintenance and a BS in Professional Aeronautics (accident investigation) From the worlds #1 aeronautical university, Embry-Riddle , but I don’t think that any of that explains my commitment to builders nearly as well as the flying planes of our builders and things we have accomplished. Henry Ford said “A man can not base his reputation on what he says he will do; only what he has done.”

I am plain spoken. to understand why, read the ‘Effective Risk Management’ story below. I have many friends who are experienced aviators who value plain talk. This type of speech also tends to offend people who dabble in aviation and would rather read polite things that align with their pet opinions. I am in aviation to share experience builders need to know, not say things people want to hear. Below are a selection of stories, some humorous, but all with a point, that give people a better understanding of who I am. From there you can decide if you choose to work with me as your engine mentor.

a) Fixing America is going to cost each of us $1.69

b) Greatest Book on Flying Ever Written, (Is your life worth $16?)

c) In defense of plain speaking……

d) Turtles and Cell Phones, 6/24/13.

e) A thought on Easter….

f) Happy Father’s Day William E. Wynne Sr.

g) Effective Risk Management – 2,903 words



9) Notes on trash from Bankrupt LLC’s:

Not all things called a Corvair represent my work or designs. Over the years, our success and willingness to share information has brought out a number of short lived LLC’s that were run by rip off artists, and mentally ill people. Particularly, there have been four businesses that made poor copies of our parts or untested garbage. All of these are bankrupt today. Because they were LLC’s they could take peoples money without any liability to repay it. Today, I have just heard that another is coming back with a new name. The story will never end as long as people don’t do their home work or believe that they are getting a bargain. You can read about one of these companies at this link: Cloudn’t have happened to a nicer guy……

I warn people all the time not to buy things from these people, or to buy this stuff at the flymart. For examples of things no one should have bought, look at this story: Built by William Wynne? Built according to The Manual?

Let me be absolutely clear, that I will be polite to people, but I will not work on, offer advice on, or help with products made by bankrupt people that I considered vermin. If you have one of the engines from these LLC’s you are out of luck. I will not allow you to join our ‘Zenvair’ group nor will I allow you to attend any of the Colleges. This isn’t out of spite, it is to protect these builders lives. They all want to put a band aid on their bad purchase and make it “good enough to fly.” A band aid isn’t going to do it, an amputation is in order. People who blew $12K on Junk don’t want to hear this, they are still looking for a cheap out that doesn’t exist.  I will not assist them in the delusion that they have found one.

The Zenith Builders and flyers website has a small number of old posts from people who bought trash like this for their projects. If you look closely, these people offered great testimonials, but later abandoned their builds. On the same sites, I have builders like Larry Winger and Rich Whittington sharing that the same people took their money and delivered trash. Some people still don’t do their home work.

Below is a photo of a heavily damaged Zenith 750 with a Corvair in it.  At first glace you might think it was the work of one of our builders, but it is not. The photo was sent to me by the insurance agent who wanted to know who much it would cost to repair. I told him I wouldn’t touch it for any price.

The problem with the plane is that the owner bought from the wrong people, and later wanted a ‘band aid’ fix, and tried to alter his engine to look more like the ones we teach people to build. Looks don’t count, function does. This plane had a rear starter that deleted the harmonic balancer. This required a goofy motor mount to clar the ring gear in the back. After the builder had a number of failures with the original starter, the builder bought another crank from another LLC in Georgia and tried to set up the plane with front starter parts bought second hand. On one of the first flights after the band aid was applied, the entire prop hub assembly and the prop came off the plane in flight and it crashed. The reason for this was probably something as simple as having the wrong flange on the replacement crank. The owner didn’t tell the insurance company that he had applied the band aid, but they found out anyway, and when they did they started talking about voiding the coverage. All of this could have been avoided by doing some homework before the original purchase, or just starting over when he realized his mistake. This is why I don’t help people put band aids on things that need to be amputated.

Just one thing to look at: The two down tubes in the mount that support the cabin structure. Note that they are actually broken. Look closely and see that they had a direction change and a butt weld right in the middle of the tube to clear the original rear starter set up. That is pure trash put out by people with no education and purchased by people looking for a bargain.  I am not here to serve such people. I believe that people have a human right to end their lives, but this doesn’t require me to assist them in doing so.


2011 Outlook and Philosophy


I wrote the following words on our traditional website in January 2011.  I am reprinting them here because I want to have them as a stand alone story that I can link to, and because I think that they are a good piece of ‘plain talk’ and commentary. They cover building and business philosophy, and they are just as true today as they were when I wrote them. People who have not met me should read the 9 points at the end, they will make many things about our approach easier to understand.- ww.


Corvair Outlook 2011


I started typing this update on January 20th. On that date exactly 50 years ago, JFK gave his inauguration speech including the famous words: “Ask not what your country can do for you, but what you can do for your country.” It is a very stirring speech, yet most people have never seen it in its entirety. It is well worth taking the time to watch it on the Internet. A majority of Americans, myself included, were not yet born 50 years ago. However, most of the people in experimental aviation are old enough to remember that day. Today, people are bombarded with messages at a rate that was inconceivable 50 years ago. The predictable effect is that none of it sticks, none of it moves anybody, and a few kernels of wheat are most often buried in a mountain of chaff. If you’re young, it is very difficult to imagine how powerful JFK’s speech was as a motivator to his “New Generation of Americans.”

On January 18th, 2011, Sgt. Shriver, JFK’s brother-in-law and the first head of the Peace Corps, passed away at age 95. He spoke countless times about how JFK’s inaugural speech was a summons to action for the Peace Corps volunteers. Opinions differ on the net effect of the 1960s on American culture. But on this day, it is well worth remembering that the era started with great ambition on a very high note. What words on a page could I write that would similarly charge you to take the reigns of your own aviation goals this year? While JFK’s message was a challenge to young Americans to take their place in the world, homebuilding is conversely a challenge to yourself, to essentially take your place as the cognizant commander of your path, an opportunity to measure your own worth and potential where the rewards are very real because the subject is serious, and the tasks are intolerant of lackadaisical attitudes of dilettantes and posers.

There are roughly 335 days left in this year. What you will accomplish in aviation this year is still an open question. Most people who are yet to start a project incorrectly believe that external circumstances dictate the odds of success. Let us squarely address the largest external factor; the vast majority of Americans traditionally involved in homebuilding have earned between $25,000 and $65,000 a year. The educational background and the ambitious nature of these homebuilders have previously insulated them from the ups and downs of the economy. However, our same group, due to loss of manufacturing jobs and outsourcing, has felt the real bite of this recession. A lot of magazines in our industry are afraid to say this, but it is reality. The acknowledgement of it will not deter a real homebuilder. It may alter his plans, change his timelines or readjust his goals, but if it makes a builder quit experimental aviation outright, perhaps homebuilding was not one of their more closely held dreams.

The real factor that counts in homebuilding success is internal, not external. Simply put, do you believe you can? Are you interested in a real challenge or is drifting through acceptable? Once started, will you find the task of creating things with you own hands rewarding enough to keep you going all the way? These are the only things that matter. External factors, no matter how strong they seem, are not the major determinant. The largest single factor is your determination that this will be your year and your will to carry it through. Tacked up on the fridge in our house is the simple phrase “Do not be optimistic nor pessimistic; be determined.” In the Corvair movement, your planning, determination and will put you in the company of some first class characters. You deserve to take your place among them.

Think about this: A guy can be from your hometown, be the same age as you, have the same number of kids, live in the same kind of house, etc., but just because you bought the same kind of car he bought, no matter how unique or sporty, in reality, you have nothing of substance in common with this person, you’re merely two car consumers. You both might be great guys in your own right, but merely owning a product in common, no matter what advertising agencies want you to believe, doesn’t give you a real connection, or any common understanding. Conversely, if you choose to build and work to create something as unique as a homebuilt aircraft, the story is totally different. A person of a different generation living in a different place and perhaps even speaking a different language who also chose to build an aircraft overcame the same self doubts and pessimism of people in his day-to-day life, learned the same skills and met the same challenges, and is certainly a brother of yours. The external differences in your lives of circumstance and place, things that were not your choice, are not what define you. Your desire to build and your determination to see it through speak volumes on your character that situation, circumstance and consumerism will never reveal.

If the economics of the past two years gave you pause, made you stop and look at the choices we all make in life and truly examine the alleged rewards of typical consumer goods vs. real challenges and adventures in life like homebuilding, then some good came of it. Anyone reading this can decide today that this will be their year in aviation, the year that was the turning point, from which they made real and steady progress. Likewise, everyone reading this is fully capable of spending the next decade in front of a TV or computer screen, entertaining themselves. I don’t judge people by their choice. I have more friends in the latter category than the former. My sole point is that I know for myself, happiness lies in the hours spent in the shop, not in the living room. I am here to work with anyone who feels the same way.

I don’t like to dwell on it, but I’m middle aged now (much, much, much older than Grace), and I’ve lived long enough to look back with some perspective on choices I’ve made. Buying something has never made me happy like creating things does. Nothing I started that had a certain positive outcome felt rewarding when I got to the end. Only challenges ambitious enough to contain the possibility of failing resulted in feelings of victory and accomplishment at their successful conclusion. This isn’t particularly insightful; we all know this at some fundamental level. Reading this drags the thought out front and center. Will you define your challenge and make your plan tonight, or will you have another year drift by?

This month brings the Superbowl. I was born in Pittsburgh, and have been a fan back to the Mean Joe Green era. I am sure Grace and I will watch the game somewhere in the company of both aviation and non-aviation friends. After the game is over, I may not watch another game for a year or two. This doesn’t make me a better person than my friends who will spend countless hours on the couch holding a remote. It just makes me different. At the end of each day, I would just prefer to be one day closer to flying something I built with my own hands. There is nothing wrong with spending your hours in either method. The only tragedy would be knowing that you are a builder, but you didn’t take your shot, for reasons that will seem small and petty when the possibility is finally gone.


Our Work In Print: The Hat Trick – BPAN, Sport Aviation, Kitplanes

2011 started off right with three major publications running very favorable articles about our work with Corvairs or our expertise with aircraft systems. Tim Kern, the most engine savvy writer in the EAA’a stable, wrote a very nice piece about us for Sport Aviation. Rick Lindstrom, who has written for Kitplanes for more than 20 years, wrote a piece focused on our collaboration with the other members of the “Corvair Consortium:” Mark Petz, Brother Roy, and Dan Weseman. The Brodhead Pietenpol News enjoys one of the largest circulations of the Type Club newsletters. It is produced by Doc and Dee Mosher and is available by visiting their http://www.Pietenpols.org Web site. If you want a look at his picture, it accompanies the Introduction Doc wrote for our Conversion Manual. Ryan Mueller and I teamed up for a very lengthy article on weight and balance calculations for BPAN. These publications vette their sources on long articles carefully. It is an achievement to be in any of them. Three in a month is unheard of. Many alternative engines and their promoters go 5 or 6 years without this kind of exposure. We got it not because I am brilliant nor charming. We got it because I worked very hard at becoming educated in aviation, I have been doing this for 22 straight years, and I have always been willing to enlist the support and acknowledge the input of other qualified people of good character. I mention it here so builders understand that I’m glad to give credit where it is due.

As you might suspect, all of the above added to the usual post-holiday return to building, and temporarily swamped our email and telephones. We were getting more than 50 emails and 50 calls a day. This stuff always arrives in a wave that leaves a new high water mark, but subsides to a normal tide shortly. If you are one of the many people who sent us a message, be assured that we are working our way through all of them.

To complete the picture, I also have to mention that such popular commentary in print always brings out the negative lurkers on the Internet. For reasons that are most probably related to emotional injuries suffered in unfortunate childhoods, there are a handful of people who cannot tolerate the successes of others, no matter how well earned the praise might be. One of my least favorite things these people do is type posts to Internet groups telling people that we are “Probably out of business” when anyone remarks that I can be difficult to reach on the phone.

Here is a test: Your best friend comes up to you and says you need anger management training. If your first reaction is to tell him to shut his pie hole and mind his own business, he is probably correct. Several years ago, in the interest of becoming a better person, I attended an anger management series hosted by an acclaimed master, nationally noted for his highly successful work, particularly with veterans. The man had the demeanor of the Dali Lama, the heart rate of an Olympic marathoner, and the stoicism of a Greek philosopher. While he stared out the window, he asked me to cite something that really ticked me off, and I mentioned people making mindless negative comments on the Internet. A smile crept over his face and he casually said, “I hate those F___ heads also.”

Above, Mark Langford’s plane on our front lawn on a chilly morning. I took this photo from our front porch. Our hangar is on the right side of the photo. Behind Mark’s plane is a drainage ditch. This is the edge of our airport’s 150′ wide, 2,800′ long grass runway. When I tell people that we live on a runway, I don’t mean it metaphorically. We have lived here the past 5 years. The house is a modest size and the 2,400 square foot hangar is an older metal building, but I did work past midnight six days a week for 15 years to get to this point. It was a long odyssey with a lot of high points and a few low ones. After 22 years of daily work in this field, it initially ticks me off when a person who has never met me questions my commitment to experimental aviation. In the end, I just feel sorry for such a person because they don’t understand having a calling in their life that they devote themselves to without reservation.


While it is never going to stop people from typing messages about being out of business, let me review a few things for people who have not yet met us: There are a lot of good reasons why I am not ever going out of business.

1) I have been doing this for 22 years, and we are well known and respected in industry circles.

2) We don’t have any business loans nor any partners or creditors. We are not looking for, nor would we accept, any investors. We have all the money we need.

3) We operate a thrifty and simple life. I can, have, and continue to be easily capable of running the Corvair movement while deficit spending for months, and even years at a time. I have very specific non-monetary goals in experimental aviation, such as having 500 builders who have each flown more than 250 hours. I have been and remain willing to expend our resources to achieve these goals.

4) I have never been sued, named in a suit, or seriously threatened. I have been the most vocal advocate of making people aware of the risks involved in experimental aviation. This insulates us from frivolous or harassing action. Additionally, we enjoy the support of a number of highly accomplished corporate lawyers in our family, starting with my older sister. From childhood, my siblings and I were trained to be mutually supporting without reservation. This now extends to our spouses. My sister is glad to defend us for nothing.

5) I have first class heath and disability insurance. I have just had an extensive screening and have been found to be in outstanding health. I have never smoked and I gave up drinking years ago. My father is 85 and going strong. I am 48 and have every reason to believe I will live as long.

6) Although I am a pilot and an avid motorcyclist, I am well trained, experienced, and well beyond the point of taking stupid or unnecessary risks in life. When it comes to things that have killed countless pilots – showing off, get-there-itis, and peer pressure – I am immune.

7) I have known my wife since 1991, we have been together since 1999, and married since 2005. She loves me despite my faults. My work will never be interrupted by divorce.

8) I am not self destructive; I don’t gamble at all, take drugs or medications of any kind. I never ride without a helmet, and usually fly in a fire suit. I do not argue with drunk rednecks, wrestle alligators, spray imron paint, or mock 300 pound bikers who can’t kickstart their shovelheads. At 48, I can no longer die young nor leave a good looking corpse. I am now resolved to live a long time.

9) While my work is not all fun, it is very rewarding. In 2000, I was lured into a certified aviation day job by a paycheck that was six times more than what Corvair work was generating. In a few months I returned to full-time Corvair work, because my need to do something important and creative was greater than my desire for comfort and consumer goods. We have made countless friends from a collection of the finest people you could hope to meet. When I was younger, I would have been depressed to think that my life’s work would largely fall into one area. Today, I actually consider it something of a privilege that through persistent hard work and the support of family and friends, I can actually focus my efforts on a single front and see how far I can advance the experience of building and flying.

These are the nine factors that tell everyone in the Corvair movement that I am in it for the long haul. Anyone who suggests otherwise has an axe to grind or should read the paragraphs above a few times. If you are on an Internet list and anyone suggests that the fact I don’t answer email the day it arrives means I am no longer in business, please cut and paste the above paragraph to your group. -ww

Zenith 601XL Builder Woody Harris at Copper state flyin.


Above, the 601XL of Woody Harris. It has flown all over the country on a 2,850. Note that Woody is from northern California and the photo above is at Kitty Hawk NC.

For our friends out west, Woody Harris, “our man on the west coast”, Called today to say that he flew from Vacaville CA to the Copper state fly-in in AZ, by way of Big Bear. He was airborne about 7 hours on an uneventful but scenic flight.  You can read more about woody by clicking on this link:


Zenith 601XL-2,850cc, Woody Harris


Woody had his first forum on Corvairs today, but he will be on hand this weekend to answer any question on our work with Corvairs. We keep him equipped with manuals and DVD’s for sale at events that we can’t get onto our own calendar. If you have not had a chance to meet him, look him up, he is friendly, knowledgeable, and good company. -ww.

FlyCorvair.net tops 300,000 page reads.


A few nights ago, the counter on this website went over 300,000.  Not bad for a very specific subject matter and 22 months of stories.  The company that provides the software just updated it so I can now tell how many different email addresses (but not which specific ones) read the site in a day. Yesterday set the one day page read high score at 1,622. This came from 677 different email addresses. Part of this was people reading the links to older stories more than once.  On a typical day we have about 1,000 page reads from 550-600 different email addresses. While almost all of these people are aviators, a number of them are probably not yet Corvair builders, just people reading popular commentaries, like the one on Cessna’s throwing in the towel on the C-162. By comparing readership on those stories with the levels on pure tech. posts, I would guess that we have 400-450 Corvair builders that read the website nearly every day.

The total count on stories is now about 370.  If you take out the Mail Sack, and some of the things like College notices, the three stories about our Dog, the pure building philosophy stories and my bitching about people who drive while texting on cell phones, the president of the EAA and Chinese parts, you still have at least 225 hard core technical posts and informative pieces, that will remain quality information for a long time.

.As always, I encourage anyone to write in with a comment to write it in.  We are always glad to share the perspectives of builders, their experience and photos.  For now, I am headed back out to the hangar to make a few more things to get in the mail tomorrow.-ww.

Corvair Oil System, information on oil pressure gauges.


A friend of ours who is building a Zenith 750 wrote in with a quick note asking about oil pressure gauges and senders. I pulled together this general set of notes on oil pressure measurement and instruments as a good resource on the general subject. Over the years Corvairs have flown with just about every kind of oil pressure instrumentation imaginable. Going back to my point of Principle vs Preference. On this subject, it mostly falls in the category of preference.

The Builders specific question was focused on sending units for electrical gauges, and their reliability. If I had to pick one brand over another, I will say that I have never had an issue with the senders that are used in Autometer gauges. VDO is usually trouble free, but I have personally had one mess up, and it caused a lot of work with it’s erroneous information. Goes without saying, I wouldn’t use one from the land of Chairman Mao.

Some people are concerned about mechanical gauges bringing oil into the cockpit, but in actual experience, I have never had an issue with it. The line itself is 1/8″ on the outside, but only 1/16″ on the inside, and I generally put a #80 hole in a restrictor, at the engine, so even if the line came off, the flow rate is about 1/2 gallon per hour. For the record, I have never seen even the poorest mechanical line installations leak. You can take the nut off at the gauge with the motor running, and it does not “spray” oil, it just oozes, and even when the engine is hot, the oil really isn’t after six feet of line.

Below is the close up of the mechanical oil pressure gauge I have in the Wagabond. In addition to all the other things I like about mechanical gauges, I like the fact the needle covers a 300 degree arc, allowing you to see very fine changes. The gauge below is $54.97 from summit racing.

Auto Meter 5721 - Auto Meter Phantom Analog Gauges

Now get a look at the next part, which is an analog electrical gauge. My primary complaint beyond the fact it is electrical is that this type of gauge is only a 90 degree sweep, making small differences had to see. They also cost about twice as much as mechanical after you get the sending unit. It is priced at $69.97, but the sender is about $40.  I buy Autometer because of the tiny letters at the bottom of the instrument that say “made in USA”

Auto Meter 5727 - Auto Meter Phantom Analog Gauges


For Builders interested in digital instrumentation, Google the name “Dakota Digital”. Below is one of their instruments, but the come in many different varieties, all made in the USA. They have a website you can buy direct from, it has many choices. Just a reminder, never mention to anyone on the phone while ordering from a non aviation company that you are building a plane.  Summit will actually black list you. The people answering the phone have $9/hr. jobs, so don’t jeopardize anyone’s just scraping by living by saying that on the phone, and having them get in hot water for not turning you in. It is an annoying fact of a litigious society, but you are not going to fix it by getting a single mother just above the poverty line fired.

If you would like to read a two part story about the simple panel I built for the Wagabond, get a look at these two following links:


Inexpensive Panel……..part one.


Inexpensive panel…….part two.


If you would like to read a story about Andy Elliott PhD arguing with ww the A&P about instrument choices, look at this one:

“William, you ignorant troglodyte”…….(instrument options)


The story below has comments on oil pressure errors in electronic instrumentation. That part is 2/3rds of the way down at the picture of the Corvair/701.


MGL vs Corvair ignition issue


As you are looking at parts of the oil system, I have reprinted the numbering system of the parts in the oil system for reference here:

Rear oil case group (2000)

2001- Rear oil case casting

2002- Rear oil seal

2003- 5/16 hold down hardware

2004- 3/8 hold down hardware

2005- Case to block gasket

2006- Harmonic balancer

2007- Balancer bolt and washer


Oil pump and regulator group (2100)

2101- Oil pump assembly

2102- Oil pump gaskets

2103- Oil pressure regulator piston

2104- Oil pressure regulator spring

2105- Oil pressure regulator plug

2106- Plug washer


Below is a good article of flight ops with comments on oil pressure indications:


Thoughts on cold weather operation, minimum oil temps, etc.


Below is a short guide on what oil to use:


Notes on Corvair flight engine oils.


Below is a visual reference to where we take the oil pressure on the Corvair engine:


Gold Oil Filter Housing, Standard and Reverse


Below has notes on how the pressure bypass works:


High Volume Oil Pump


Have a pleasant and productive evening.-ww

Cessna’s Chinese adventure a failure.


3,000cc PC Cruiser builder and Aeronautical Engineer Sarah Ashmore shared the following press release:


“Cessna President and CEO Scott Ernest is signaling that Skycatcher, the company’s low-cost, Chinese-built light-sport aircraft, has been relegated to the history books. “There’s no future,” Ernest said when asked about the aircraft at a Cessna press conference Oct. 21 at the NBAA convention in Las Vegas. Asked if that meant the project would be discontinued, he replied, “No future.” Skycatcher was launched six years ago with great fanfare by Ernest’s predecessor, Jack Pelton. Offered at an introductory price of $109,500, the aircraft attracted 720 orders worth more than $75 million in the first three weeks after launch, and backlog ultimately topped 1,000. But the project was bedeviled by manufacturing problems at its Chinese partner. Cessna also was forced to raise Skycatcher’s price, which caused its backlog to evaporate. Ernest was more upbeat on two new signature projects at the aircraft builder. The Citation Latitude mid-sized jet is on track to make its inaugural flight in the first quarter of 2014, and the Citation X — billed at the “world’s fastest civilian aircraft” — is expected to win final certification in March.”


In with a big bang and out with a whimper, thus ends Cessna’s 162 Skycatcher, an aircraft that was promised to set great standards in general aviation, ends up never even getting to heavy production in spite of having 1,000 deposits.

Note that the reason for the failure is: “the project was bedeviled by manufacturing problems at its Chinese partner” .  Where is all that Chinese workmanship and craftsmanship now? Please note that this project, specifically shipping it to China, was the brainchild of the former CEO Jack Pelton. In case you are wondering what that guy does for a living today, why of course he is head of the EAA. Does he sound like the person who really has his finger on the pulse of General Aviation?  Really understood traditional American aviation values? Absolutely not. Pelton was willing to sell out all the craftsmen who worked in Wichita for cheap Chinese labor if it could make a buck. If you work for a living, and you are an EAA member, you need no further proof that if there is a corporate dollar to be made, your interests, skills, support of our organization, and your respect for your fellow working Americans mean nothing to him. 

So Cessna finds out that they should have had these planes made in the USA. The corporate elite will blame the 2008 economy, but it is fair to ask what part of our economic troubles and slow comeback belongs to all the CEO’s like Pelton who shipped our manufacturing base overseas for their own profit.  (These are the people who can’t understand why a guy who had his skilled craftsman job outsourced in 2005 and now works in a $7/hr service job finds taking his family to Oshkosh unaffordable.)

And let us not forget the 1,000 wealthy buyers who certainly didn’t care where their new $100K toy was made, as long as they got to have it. We are all forced at times to purchase some imported things from places we don’t like, but a person who can buy a $100,000 toy with discretionary income isn’t forced to do anything. If you buy a pair of imported sneakers once a year, you are not giving away the same jobs nor fueling the trade deficit like a guy buying a Skycatcher.  I am sure plenty of these 1,000 eagerly awaited delivery while driving around in imported cars with “take back America” stickers on them.  If they don’t care that their imported Cessna would be built by $2/hr labor in a police state while the unemployment lines in Wichita got longer, then where do they draw the line?  If Jack Pelton had struck a deal with Bin Laden’s family to make Skycatchers at the family run IED plant in Pakistan, I am sure that 50% of the ‘patriotic’ 1,000 buyers would have asked “can I still get my Skycatcher this year at the same price?”

If I seem to be harsh on this, it might just be that you missed my long standing and vocal hatred of the C-162. When the plane lost both the prototypes in spins that Professional test pilots could not recover them from, I was glad to question if this plane was right for student pilots; When the EAA accepted samples to fly young air academy students in, I was among those that said you can’t tell a 15 year old to study and become an engineer if you show him a plane built elsewhere, and tell him he will never have a job producing them; I have pointed out countless times that there is no such thing as Chinese business ethics and quality control when it comes to making cheap things for export.

So, who will make America’s light planes? You will, the working American, just as you have always done. In 1946 Cessna went from war production to making 30 C-120’s and C-140’s a day, without any issue at all. The greedy corporate scum like Pelton had 6 years to tool up and they couldn’t hardly make 30 aircraft per year in China. The only important difference is that the Cessna ownership in 1946 respected their workforce of Americans, and 60 years later Pelton had all his faith in the best $2/hr Chinese workers he could buy. Moving forward, it is clear that Cessna has now abandoned the “affordable” aircraft market. This makes no difference to any homebuilder. In 1946, Cessna was something of a partner to American labor in producing that generation of affordable American aircraft. Today,  they have proven to be a worthless element. Each of us, developing our own craftsmanship, will work in our own one plane factory and produce our own aircraft. This is how American labor will build this generation of affordable aircraft. We don’t need cheap labor in China, we don’t need greedy CEO’s and we don’t need any membership organization that is headed by a person who fails to understand this.-ww.

22 hours until CC#27 sign up closes.


Here is your last official notice on CC#27. While the frequency of notices resembles a PBS fund drive, I want to say that we always have one or two people who miss the notice and sometimes the dead line. Don’t let this happen to you. If you are sitting on the fence, we are getting to the wire. The sign up for #27 has been open for 100 days: you now have less than one day left to sign up. Click on this link for more info:

50 hours until CC#27 registration closes.


CHT part #5, flight data from Zenith 750


Here is some very detailed flight data from  2,850cc Zenith builder/flyer Jeff Cochran. It is a very good and useful piece of data collection, with many fine points included. I took more than an hour to examine the charts in detail. Jeff’s accompanying letter had a lot of good flyer feedback in it also. He is straight forward and methodical in his evaluation to fine tune his specific installation. I share with builders some larger perspective to put this data in a context where you may find it easier to appreciate.

Jeff and his lovely wife at CC#16. They have attended many colleges. Jeff ran his engine at CC#19, and will likely flying it back to CC#27 for it’s public debut in front of fellow builders who fully understand the achievement of completing and flying your own plane.


For a little background on Jeff and his plane, read the story by clicking on this link:

New “Zenvair-750″, Jeff Cochran, 2,850cc engine, N750ZV


One of the things that came to mind when looking at Jeff’s data was the early work that Mark Langford did in data recording in his KR-2S. (Mark was the first pilot to be awarded The Cherry Grove Trophy in 2008) Eight years ago Mark was one of the first guys to publish this kind of information from his Grand Rapids unit. It was read by many builders, and was a unique resource and sparked a lot of discussion, and also squashed a lot of pet theories among the internet armchair opinion crowd. Let me use the photo below to illustrate an interesting distinction between the data sets:

Above is Mark Langford’s plane with the cowl off in a photo from Corvair College #16. The airframe and the engine installation were unique in many ways. The plane was built as a personal expression of his creativity. Several other KR’s followed Mark’s build and utilized ideas that worked on his plane. Since this segment is focused on CHT, look at Mark’s cooling, a twin ‘plenum’ style system that worked well in his plane. His cowling was one he made a mold for, he used a rear starter and belt driven rear alternator, along with a remote cooler. These ideas served him for more than 1,000 flight hours in his KR, however some of these ideas would have limited applicability on other airframes. The 5th bearing on this plane is the same design I am using on our Wagabond, but almost all of the other subsystems on the Wagabond are common to our standard 601/750 installation. The Kr is a small fast aircraft that operates in a different flight envelope.


What makes Jeff’s data unique to me is that it is all gathered around off the shelf parts on a very popular airframe. KR airframes are highly individual. The have a choice of airfoils, wing areas and spans, different landing gear, fuselage lengths and widths,  and several canopy styles. By comparison, no such variation exists with Zeniths. What one builder learns can be directly applied to another’s aircraft with predictable result. Virtually all Corvair/750 builders utilize standard parts from our catalog, and assemble them according to our installation manual. Additionally, a 750 is the largest and slowest climbing aircraft Corvairs are commonly used on. One can be reasonably sure that anything that works in a Corvair/750 aircraft cooling/cowling system will also work on any faster smaller Corvair powered airframe, whereas the reverse is not frequently true.

In Jeff’s letter he references comparing notes with Gary Burdett. If you have not seen it, we have pictures on this site and his story is at this link: Zenith 750 Flying on Corvair Power, Gary Burdett, Illinois . Because their two airframes and engine configurations are very close to each other, They can utilize shared information to fine tune each of their planes. This goes further than just having a cowling in common. Details like both aircraft having a gold oil filter housing means that data like oil temp is taken at the same spot on both engines, giving very direct comparisons.

This effect is true for all Corvair/Zenith combinations to a degree that is not possible with individualized aircraft like KRs and to a large extent, Pietenpols. Both of those airframes have active and well run internet groups. Zenith runs it own gigantic webgroup for all of its builders. To give builders working with the Zenith/Corvair combination a specific spot where they could directly exchange data and notes, we set up a specific discussion board just for them. You can read about it by clicking on this link: ‘Zenvair’ Information board formed . The quality of discussion there is very high for several reasons. It is an invitation only group and it is very effectively organized and moderated By Phil Maxson. You can read about phil at this link: Guest writer: Phil Maxson, flying a 3100cc Corvair in his 601XL. Jeff, Gary, Phil and other ‘Zenvair’ builders can directly work with each other in a setting where everyone is a serious builder.

The two links below are the Data that Jeff refers to in his letter. Interesting to have independent confirmation and data to say that the alternator location doesn’t make much of a difference in cooling. We sell the front alternator (group 2900) and Dan sells the rear alternator (Group 2950). For many years people speculated that moving the alternator to the back would cause a huge reduction in temps. Both Dan and I told people this wasn’t likely because non-plenum cooling systems with round inlets are very good about sharing all the incoming air no mater which hole it arrives through. Jeff’s numbers confirm this and show the limitations of ‘eyeball & theory’ vs accurate back to back testing.

Many people who have never met me picture me as an opinionated zealot advocating some type of ‘my way or the highway’ mentality, unable to change perspectives. While I do have principles that I will not compromise on, 25 years of working on planes has given me the perspective to understand what is an issue of principle and what is just a matter of preference.

Many closed minded people act like zealots simply because they don’t have the experience to differentiate between these two. Picture the guy who frequently says “That will never work”; He is proven wrong by the first guy who makes a trip around the pattern with the idea. Conversely, when a guy says ” might work, but I prefer not to do it that way because….” he is speaking from experience. On matters of preference, I am open minded. I have a 5th bearing design and sell front alternators, but our production engines feature Dan bearings and mostly rear alternators. I assembled both Jeff’s and Gary’s engines. They are very similar 2,850s yet one has a Dan bearing and one has a Roy bearing.  These are all matters of preference between proven parts. I am if favor of builders making educated choices. The operative word ‘educated’ starts with real data like Jeff is presenting here. -ww.


Jeff’s data charts:


CochranPDFGraph1013 Graph Link


CochranXL101813 XL worksheet link


Jeff’s Letter:


“William, Since you are doing all of the CHT and cooling articles, I thought I might update you on my progress.

I have dropped the bottom of the cowl so that I have almost 4″ between the bottom edge of the firewall and the bend in the cowl bottom.  By my calculations this gives me a 2.4 to 1 ratio.  I still want to up this a little.  This is very close to the set-up Gary Burdett is running.  We should be almost exactly alike now with one or two exceptions.  I went ahead and ordered and installed the rear alternator kit from Dan.  The front bracket is still in place just in case I need to go back.  I am also flying without the leading edge slats.  My inlets are 5″ and still raw cut edges with no ring inlets.

Sensor set-up has been changed.  For a while I ran a thermocouple in each of the thermowells like the GM thermistors and a 10mm ring on the thermocouple bolt. I also had a 14mm ring on the corresponding plugs.  So three sensors on cylinders 1 and 6.  The plug was always the highest, the bolt the lowest with the thermowell location in the middle.  I discontinued the two bolt locations and moved those sensors to plugs 2 and 3.  Somewhere I had heard that cylinder 3 was always the hottest, but my data really does not support that as far as the plugs are concerned.


My Dynon D180 saves data on almost every possible parameter you can attach a sensor for.  I download the file after every test flight.  The first page of the attached workbook is the total raw data. On the second page I delete all of the data that is not really recorded (the Dynon seems to make up data when no sensors are attached).  Then on the short version, I delete everything I am not interested in at this time.  I chart the CHT’s and since the alternator move the electrical data. I have attached the excel workbook file.  But just in case you really are the computer troglodyte you claim to be (which I really doubt) I have converted the CHT chart to .pdf.  

The alternator move as you have often said did not seem to make much difference in cooling. Logically that was so hard to believe I just had to prove it to myself,  You probably have realized by now that some of us are hardheaded that way.  Cylinder 6 is always much cooler that cylinder 1 so I tend to concentrate on cylinder 1 numbers.  Since the 380 degree number has been posted by you and I have seen it on the car sites also, I set my goal of try to keep the temp measured in the cylinder 1 thermowell (where the car was measured) as my normal max goal.  My current set-up has been achieving that limit.  I still plan to smooth and ring the inlet some time in the future.


I’m still planning to fly to Barnwell (weather permitting).  Either way, see you there. –Jeff”