Brand New 250 page 2014 Manual- Done

Builders,

I went to the print shop yesterday and picked up boxes of our new manual. This is a very large, entirely new Corvair Conversion manual I have been working on for 18 months.

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Rear view of a 3000 cc engine with mechanical fuel injection.

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It is based on the new numbering system that we introduced last year, It is much better organized than our previous manual. It has twice the page count, but it has a more compact font and smaller margins, yielding 3.5 times the content of the last manual, The word count is now 103,500. Every photo has a detailed caption, much of the book is in color, it has greatly expanded sections on installations and includes checklists and operations data.

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Grace has delayed mailing new manual orders that have come in recently to wait for this. If you bought a manual in the last 90 days we will get you a new one after Oshkosh for reduced cost. If you hold an older manual and would like to upgrade, just send us an email with “Manual upgrade” in the subject line and the number from the cover of your original manual please include your mailing address.  After Oshkosh we will send you a note about the cost of the upgrade before we ship it to you.

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New Builders can directly go to the manual link on our products page: http://www.flycorvair.com/manual.html to order their manual. We have raised the price to $69, from the $59 cost that we had on the last manual for 10 years.- ww.

 

 

Great moments in aircraft testing -2003-2004-2008

Builders:

In two weeks we will be headed back to Oshkosh. Once there we will be surrounded by hundreds of companies that will all attest on a stack of Bibles that they have carefully tested all of their products to protect the safety of their customers. In with these people will be at least 30 companies selling engines. Every single one of these companies will tell you without blinking an eye that their engine power output numbers are the result of careful Dynomometer testing. Almost all (90%) of these companies are lying about this.

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Traditional dyno testing is expensive, and a bit of a production to adapt an aircraft engine to. To learn much, it requires hours of evaluation, and runs at different conditions. Any company that does this would be justified in taking a photo of this milestone in their company history…….except you can politely ask to see a photo of their engine on a dyno, and of course they will not be able to produce a single image of their engine running on a dyno. I actually had one company tell they had done 100 hours of testing, but had forgotten to take a single photo of it. In an era where nearly every human has a cell phone that is also a camera, please tell me who would believe this?

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There are many kinds of dynos. Basically they all apply a load to the engine, and then measure the equal and opposite torque reaction resisting this load. No Dyno measures HP; they measure torque. HP is a calculation based on torque and RPM. If you building a plane, you don’t need to know this, but ideally everyone selling engines would, (but they don’t). A real motor head, like yours truly, knows this stuff. Combine this with some basic fabrication, and “Taa Daa!” the $500 dyno. Our dyno used the prop to generate the load,  allowed the engine to rotate on it’s crank axis by using a front spindle from a Corvair car, and measure the torque with a hydraulic cylinder. Later we simplified it further with an electronic scale for measurement. Using a digital optical tach, the accuracy measuring HP was within 2%

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I didn’t invent this kind of dyno, it has been around a long time, pictures of them in 1960s Sport Aviation magazines. This isn’t even the simplest kind of dyno. In one old Sport Aviation there is a picture of a Corvair  hanging on a steel cable turning a prop, with a wooden arm touching a scale. Yes that works also. The pictures of our set up have been on our webpage for more than 10 years. It would be very easy for any company selling engines at Oshkosh to have built their own version. Easy, but not as easy as telling people they have hundred of hours of testing, but forgot to take any photos.

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2003- Above, Oil system testing at Spruce Creek airport, 2003. We were testing how much pressure loss the cooler had when the oil in it was cold soaked for an hour at 32F. Testing like this is serious business. Note that Gus Warren liked Becks Dark, and I liked Michelob. Lot’s of companies like to have the appearance that they test products: they put people in lab coats and have them make scientific faces.  I don’t care for appearances, I just want results, and the picture shows we drank beer while we let the oil cool off. I can put on a lab coat a lot faster than a salesman can become a motor head and teach builders anything valuable.

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2004- Above, an O-200 on our dynamomemter; test crew from left to right, above: Gus Warren, Detroit Institute of Aeronautics, A&P 1990; Steve Upson, Northrop University, A&P 1976; yours truly, William Wynne, Embry-Riddle Aeronautical University, A&P 1991. While the way we dress may be slow to catch on in high fashion circles, we certainly know our stuff about all types of aircraft powerplants.

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2008- Above, Kevin and I are standing on my front yard, wearing jackets. We were waiting just before sunset for a rare weather phenomena to occur: a perfect standard day of 59F 50% relative humidity and a pressure of 29.92. Any time you read a dyno report and it says “corrected horsepower,” they’re making a calculation, sometimes accurate and sometimes not, to adjust for their test conditions not being at standard atmosphere. Because we live in Florida near sea level, there was actually  three occasions in four years when these conditions were met on testing days, and all our results we calibrated against these standards.

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How you can build a Dyno for $500 if you know how they work and you can weld:

Dynamometer testing the Corvair and O-200

A page devoted to all kinds of testing:

Testing and Data Collection reference page

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Questions from potential builders:

Builders,

Here are some questions that came in as comments on other stories:

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Frank Stephenson writes:

“While there will be many different results, I am wondering what the average time before overhaul may be. Also what are we looking at cost wise for one of these engines and the average cost of an engine mount? I am considering selling my current conventional geared C-172 with a C-O300B engine and buying or building something a bit smaller and more efficient. I really don’t know anything about Corvair engines other than I know of several folks who have utilized them, but I don’t really know anything about their results. I have found, in general, that automotive engines don’t make really good aircraft engines, but some VW engines I have known of are an exception and apparently the Corvair engines may be an exception.”

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Frank, the minimum time between overhauls on a well built engine is 1,500 hours. Ten years ago we listed 1,000 hours as a very conservative figure, since then, improvements like using valve rotators have driven the life span up significantly. The Overhaul cost on the engine is very low, on the order of $2,000 to replace almost all moving parts or recondition them. You can lean more at this link: Basic Corvair information I understand that many automotive engine engines have a poor record, but I have been doing this for 25 years, and we have earned an excellent one. You can read this link: Planes flying on Corvair Power, and see many examples. For the cost of motor mounts, just look at out catalog,http://www.flycorvair.com/, and page down to Group 4200, it lists the price of every mount we make.

I know VW engines have worked for many people, but I will put the track record for reliability, power and TBO of our work with Corvairs against any VW based engine. There is a lot of information on our main webpage, http://www.flycorvair.com/. I understand that it looks overwhelming, but better too much than to little.

Here is an important point: I don’t think efficiency is a good enough reason to move to homebuilding. Lets say your Cessna does 110mph on 8 gallons an hour. There are several Corvair powered planes that can do that on 5 gallons an hour, even some on 3 gallons an hour. But even if you were to cut your fuel costs on flying 200 hours a year from $8,000 to $4,000 per year, I don’t think it is enough motivation to send a guy to the shop for 1,500 building hours. The only people that consistently succeed at homebuilding are the people who inherently would rather fly something the personally built, and people motivate by the desire to learn new skills. I have met very few people motivated just to fly less expensively who thought in the long run that homebuilding was worth it. Consider this carefully, you may have a better time staying airborne in the plane you have.

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Steve Spears

“Sir, I am currently building a RW26 Special ll and I would like to use the Corvair engine. However, some people are telling me that it is to heavy for the aircraft. What are your thoughts and do you know of anyone who has used a Corvair engine in the Rag Wing aircraft? I read what you wrote about the Pietenpol and am encouraged that I can use the engine”

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Steve, I looked at this pretty closely for an hour the other night. I tend to think that a Corvair is too big to the R-26. The 912 appears to be as large an engine as people use. Several of Rodger Mann’s designs have flown with Corvairs, but I wouldn’t call any of them an ideal match. I am guessing that a Rotax 503 is really the optimum engine for many of his designs. For a comparison of how heavy duty a Pietenpol is built, the longerons in the fuselage are one inch square spruce from the firewall to the tail post. I am pretty sure the R-26 is lighter than that.

For any plane that you are wondering about Corvair power for, the best rule of thumb is asking if the same plane has flown with a Continental o-200. If it has, a Corvair will always work in it. For a comparison of the two engines look at this link:Corvair vs O-200….weight comparison and this one:Dynamometer testing the Corvair and O-200. We also have a lot of info on comparisons to 912s at this link: Testing and Data Collection reference page.  -ww.

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Turbocharging Corvair Flight engines Pt. #2

Builders, Here is part 2:

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“Boosted” engines: If normalizing is trying to maintain 29.92″ of sea level pressure in the intake, a boosted engine is driving the manifold pressure above this. This is actually very common, and almost every single classic radial engine was “Boosted”, except they most often used superchargers to do this. A P&W 450 hp radial is known by its displacement “the 985″ is how many cubic inches it has. They make their rated power at 36.5″ of manifold pressure. Many other classic piston engines made their power at 45 -72″ of manifold pressure. High end GA engines like the GTISO-520 makes it “low power” 375 hp rating at 40″ MAP. In the big picture it is ‘turbo normalizing’ that is the oddity.

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In the car, the turbo Corvair is a Boosted engine. The 180 HP ‘Corsa’ model made its rated power at 5,200 rpm and 45″ MAP. That is about 7 pounds of boost in car-speak. Worth noting is that the same engine made 265 foot pounds of torque was down low in the rpm band, at a setting that can be used in a direct drive engine, and the turbos we have used are far better at building torque that the car original was. A 3,000 cc  engine running 40″ MAP on takeoff is burning the same amount of fuel and air as a 4,000 cc naturally aspirated engine. If that doesn’t sound dramatic, read this story to understand what kind of difference 35% more power makes on a plane’s climb performance: Pietenpol Power: 100 hp Corvair vs 65 hp Lycoming

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Draw through vs Blow through:  On a draw through arrangement, the air flows through the carb, then the turbo and on to the engine.  A blow through is turbo-carb (or injection) and then the engine. Draw through is characterized by simplicity. Our set ups are all draw through, as was the original Corvair car. Virtually all modern cars are fuel injected, and the ones that are turboed are blow through. The primary advantages are two things which don’t matter to planes, throttle response and emmisions.  One of the hidden advantages to draw through is the fuel getting fully vaporized early radically cools the intake air and makes it more dense without the need for an intercooler. Injected engines can’t do this because the fuel arrives in the intake just ahead of the valves. In one minute at full output, a turbo engine will digest and vaporize more than a pound of fuel, this has a great cooling effect on 250 cubic feet of air.

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One of the things that always comes up when you mention draw through arrangements on planes is an alarmist pointing out that every foot of the intake has air and fuel in it under slight pressure, and this is in his mind a giant fire hazard. A dozen years ago it was mentioned on the Dragonfly builder’s list that I was working on a draw through arrangement for the Corvair. The leading ‘personality’ on that list wrote a long diatribe about what a horrible person I was, and convinced most people of this by saying that no airplane was made that way.  Only one problem with his argument, it  was a complete lie.  The US built 300,000 planes in WWII; 160,000 of them were multi engine, and 32,000 of those had four engines. If you look at all the radials, the Allisons and the Merlins on these planes, You are looking at 750,000 engines, and virtually every one of them was a draw through arrangement being boosted by a turbo, a supercharger or both.  A R-4360 engine has at least forty, (40′) feet of intake piping after the blower, and every bit of it is packed with fuel and air. There are 56 couplings in that intake system that I can think of. If draw through systems didn’t work WWII would have had a different outcome.

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 For a look at some of our ground testing we did in 2004 before flight testing, get a look at this link: Testing Turbo Corvair and Rotax 912S. In some of the tests we ran the MAP all the way to 60″, which is 15 pounds of boost, or a 2,700 cc engine inhaling the same amount of air as one that is 5,400 cc (330 cubic inches) The turbo we were using was a modified Garret TO-4B with a .58AR housing, machined for a carbon seal. It worked great. Not all turbos are expensive, this one was made in the USA and it was only $545 brand new. The real cost of a full turbo system is far more, because many of the other parts like the exhaust system have to be made from very high quality materials. If you look at the price of turbos on Ebay, be aware that the market is flooded with counterfeit name brand turbos that are made in red China. A turbo counts on good materials, it often runs 1,600F on the inlet and the wheel is turning 100,000 rpm while it is working. If it breaks a blade or bearing, it feeds the metal from the compressor side right into the engine. It pays to buy the real thing, especially because the US made items are often reasonably priced.

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 We learned a lot in testing. My plan was to take the regular 2004 100 hp conversion on the Skycoupe and run it with the turbo on it and get some time on it to see what parts would need to be upgraded to last on a turbo engine.  First, let me say that nothing on the engine broke, but judging from the 1550F EGTs and high oil temps, the engine would have gotten ‘tired’ quickly with the stock conversion parts of 2004.  When I see people talking about putting a turbo on an engine out of a junkyard that was never intended to be turboed, I can only wish them good luck, because our testing indicated that any engine running in a boost condition will need the best available internal parts and systems.

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Below is a number of things our testing indicated we needed for the engine to work as a regular, long lived power plant. After each topic is a link to a story of the part we developed to address each of the issues. These developed systems also served as stand alone options that have improved regular naturally aspirated Corvairs, but the owe their origins to conditions our testing identified 10 years ago.

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Engines in lower compression and more displacement with a quench: The 2,850 pistons were developed specifically to work with turbocharging. They also happen to work very well as a dual fuel piston suited to both 100ll and auto fuel. The 3,000 cc models we developed as a spin off. read the stories by clicking on the links:

Getting Started in 2013, Part #16, 3,000 cc Piston/cylinder kits

Getting Started in 2013, Part #14, 2,850 cc piston/rod/cyl. Kits

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Pressure retard distributor: When an engine is boosted it need less ignition advance. This is done on a Corvair car with a pressure retard in the place of the vacuum advance on the stock distributor. In the Skycoupe I made a special dual points distributor that only had 25 degrees of total advance. The long term answer was the system below. As a tech spin off it will also be useful on naturally aspirated engine at very high altitudes:

Ignition system, experimental “E/E-T”

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Ultra high grade exhaust valves: We normally use 4-N stainless valves in Corvairs, but the exhaust valves of turbo motors need to be made of exceptional materal to last to a normal TBO. This is a job for the super-alloy Inconel. Mark Petz of Falcon head fame developed these in 2008.  See picture below:

Above, I hold the last word in Corvair exhaust valves. In the past year, Mark Petniunas put a tremendous amount of effort into finding a source for these valves, which are precision manufactured out of the super alloy Inconel. It has greater strength at 1,500F than 4130N steel does at room temp.

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321 stainless exhaust. Our normal exhausts are made of 304 stainless, a very high quality material, but the job is better done by 321. Very few experimental engine companies have ever used this because it is 3 times the price of 304. The link below is about our regular systems, at the bottom of this page is a photo of a 321 system I made for a 601XL test.

Stainless Steel Exhaust Systems

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high volume oil pumps: Turbo engines need more oil flow to feed the bearing in the turbo, the 5th bearing and to internally cool the engine. High volume oil pumps have been around for a long time for Corvair cars, but we developed our CNC model which has better internal alignment:

High Volume Oil Pump

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large aircraft oil coolers. Turbo engine make the oil hot, it flows through the turbo’s bearing with is one inch away from the exhaust housing which can be visibly glowing. Our Gold oil systemens serve many purposes, but they would serve a turbo engine very well and allow the use of a appropriate sized cooler:

Heavy Duty Gold Oil Systems, new cooler model.

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5th bearings: These were in development by the time we were doing our turbo testing, but we did not have one on the skycoupe. Today, virtually all Corvair flight engines use one, and I would not consider building a turbo engine without one:

Getting Started in 2013, part #1, Crankshaft process options.

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I am holding the turbocharger that Woody Harris found for our test program. Note that it has an integrated wastegate. This is a common feature on modern car turbos. However, almost no modern car turbo has the capability of being used in a drawthrough application, which is a highly desirable format for aircraft use. It took us a long time to find an expert on turbos who could properly fabricate a modern turbo, appropriately sized for our application, with a carbon seal. 

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I built this exhaust System out of 321 stainless. Its future home is on Woody Harris’ 601 XL.   He will be retrofitting his 2,850 cc engine with a turbocharger. This is the engine half of the exhaust system, and it was built in my jigs. Our regular exhaust systems are built out of 304 stainless, which is extremely durable and fairly resistant to heat flow. 321 is the alloy of choice for Turbo Systems, as it withstands elevated temperatures even better. Notice how the one pipe crosses underneath the engine to go over and meet with the other before heading into the Turbo.  It is worth noting, however, that naturally aspirated Corvair powered 601s with 2,700 cc engines have exceeded 17,000’ and have little problem with density altitudes over 14,000 feet.

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Turbocharging Corvair flight engines, Pt #1

Builders,

I am going to sweep together much of the info we have on turbocharging Corvairs here and have it as a reference page for builders, with links to other previous information I have written on the subject.

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Why put a turbo on a Corvair Flight engine? For more power. Corvair cars were the first mass produced turbocharged passenger cars. Many people who know little about cars mistakenly think it was the Porsche 911, but the Corvair Spider beat the Carrera to the market by a full 12 years. The Corvair was designed from the start with the possibility of boosting the output by putting a turbo on it. Above all, it has the cooling for this. Engines that barely have the cooling to run naturally aspirated don’t stand a chance with a turbo.

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 Our work with turbos on flying Corvairs: Most of our flight test work was done in 2005. The information was of personal interest to me, and many builders expressed an interest also. But as a reality check, A turbo on a flying Corvair was not really something 95% of builders needed. Also, bringing our test bed aircraft to airshows and speaking with builders taught me that the great majority of people who expressed interest had little appreciation of the complexity and often they had very unrealistic expectations. The best example of this was the majority of people saying “I don’t want a boosted engine, I just want it turbo-normalized” Clearly some of the sources of information on turbocharging of planes that people were reading was not written from a practical experience. Having a flying plane was done, but there was a lot of work to go before builders could understand what the motor would entail, what it would be good at, and what it could not practically do.

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Above is a 2005 overhead shot of  our test bead aircraft the Turbo-Skycoupe.  It is easy to see the stainless heat shield over the hot side of the turbo in this view. You can see more photos at this link: More Turbo Skycoupe photos

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Turbo-normalizing engines: Picture a naturally aspirated 100 hp Corvair powered plane climbing out from an airport at sea level. The pressure is 29.92″ there. Now picture the same plane taking off from Leadville CO, at 9,927′. The air there is has only 65% of the density it does at sea level. A turbo could easily put this right back, but here is the in-escapable issue: You can only do this with an inflight adjustable prop. If you tried it with a fixed pitch prop that worked at sea level, the prop would radically over speed at altitude.  If you put on a fixed pitch prop that absorbed 100 hp at 9,927′ and then tried to take off from sea leave without boosting the engine past 29,92″ on take off, the plane might not even spin the same prop to 2,500 rpm. performance would be very poor, less than a naturally aspirated 100 hp motor with the right prop. The bottom line is you can’t turbo-normalize any plane unless it has an in flight adjustable prop. They exist, but they cost nearly as much money as your motor will. The good news is that a turbo-boosted engine still makes sense in some applications, and it works with a fixed pitch prop.

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The Vne problem: Many people who like the idea of a turbo say “I want to get up high and go fast.” OK, this can be done, but here is a very real issue: Many light planes, especially experimentals, can already operate near their Vne (Velocity Never Exceed) speed. If you add a turbo to them, they will be able to fly right through it in level flight, a very bad idea. People debate this, but here is the reality that the educated side of the argument knows: Vne is based on TRUE airspeed not indicated. If you are in a plane with a Vne of 200 mph, and you are at 10,000′ and indicating 170 mph on a naturaly aspirated engine, you have no where to go. This is because your true airspeed will be 199 mph, and that is 1 mph below your Vne. Put a turbo on that plane and you can’t use it to increase the high altitude cruise. This is a very common condition for Van’s RV aircraft, and it is a big part of the reason why you don’t hear about them being usefully turbocharged. With Corvairs, the common example is the KR-2s, which can fly very near it’s Vne naturally aspirated.  If someone around the airport tells you I am wrong about this, look it up for yourself in Aerodynamics for Naval Aviators. I can’t sing nor dance, but I did learn some things in my 5 1/2 years at Embry-Riddle.

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Above, Arnold Holmes and I stand behind the engine installation on a V-8 powered Lancair IV-P. This is an EngineAir package that I helped develop from 1993 to ’98. It’s 450hp, geared, injected, intercooled and very heavily turbocharged.

 Most of the people commenting on turbocharging piston planes have little experience with it. In 1996 We took a Lancair IVP like this one on a test flight to 32,500′  I have a number of hours aloft above 29,000′ in these planes. Very few people have flown that high in light piston planes, and truly very few have worked on the engines and system that worked in this environment. You can learn a lot; example, you can easily overheat an engine even when it is 30 below zero outside because the air density is low, and it can’t take many BTU’s out of the cooling system.

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There are also many practical things that directly relate to turbocharged Corvairs such as techniques of welding 321 stainless tubing. Many new guys like to talk about selecting the turbo itself, but my experience says that the reliability of the system has a lot to do with details like how large the radius in the exhaust bends are, if the welders are really careful to come off the Tig pedal slowly and not to leave tiny ‘craters’ on the ends of weld beads, and a bunch of other details. Dozens of companies have on line catalogs to pick turbos, and people regurgitate that info all the time, but real installations have to be very carefully fabricated by experienced people.

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Get a good look at the size of the 5-blade MT propeller. Air is thin at 30,000′ and to absorb 400 hp there, you need blade area, speed and lots of pitch change . Contrary to what some people think, even though this engine was geared 2.19 to 1, it only needed 74″ of diameter to be optimized for the task.

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on to part #2…..

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New Builder ‘Cards’ and communications

Builders,

Many of you who have met us in person know that one leg of our builder records are on paper. (This backs up of computer records) Grace tends to work with the computers, but I like the Card system. It revolves around how we work with builders; Grace tends to communicate by email, I generally call builders.

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For example, If I am calling builders in the evening, I generally pull their card out of the files, and review from it the progress of their project, give them a call and cover questions and ideas with them. When I head to an airshow, I bring both existing cards and new blank ones to fill out. I find this a better way to lay out a progress plan with builders picking up or ordering parts.

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Most builders know about how our full on line catalog also doubles as a checklist for a complete engine build with all the group numbers and the part numbers in each group.  You can see it at this link:http://www.flycorvair.com/products.html. But, it is a long 10 page print out with a lot of detailed info. The Builder card is an abbreviated version of this, stripped down to just list the most popular parts that builders get from us. It leaves off all the items that come with the core engine, come from other sources like Clark’s Corvair or the Wesemans and the ordering notes.

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Yesterday, Grace and I spent a two hours revising the card to reflect all the most current part numbers. As you are giving it a look, keep in mind that the total of the prices listed is very high if totaled because several choices for systems are listed. Example, both E/P and E/P/X distributors are listed, but your engine needs only one. Likewise, there are four stainless exhaust systems listed, but obviously a plane needs just one. If you are looking at the Card and something isn’t clear, the first stop is back at the main catalog page, where the descriptions are expanded and there are further notes. I wanted to give new builders an advance look at things they will likely need from us.  Note that some items don’t have prices, these items are place holders that may be developed later.

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EngineBuilderCard1060614

tying

 

EngineBuilderCard2060614

Here’s a link to a pdf which might be easier for some to print:

EngineTwoPageCard060614PDF

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Communications:

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In the last 90 days we have been hit with both, a number of family obligations and a deluge of email and calls. The family obligations are the same things that nearly everyone faces at one time, and we appreciate the people who expresses understanding. The Email has been caused by a string of favorable magazine articles and interest coming off the four 2014 colleges. I understand that it can be frustrating at times to work with this, but we are putting great effort into getting back ahead of the curve. The new builders cards above are a very small part of a comprehensive re-organization, all done to make things work smoother. I have taken behind the scenes, but real, steps to prioritize existing builders. If you are a builder who I still have to call back, you may not feel this yet, but we are working on it.

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A while back, I wrote two stories that explained how we are a small mom and pop business in an industry characterized by big flashy, often short lived outfits. We have a different mission, approach and capability. For people who can meet us half way, there are rewards you can’t get from salesmen. The two stories are: Back from the road, notes on Communications and Improving communications……a little reading goes a long way. Below is an excerpt from the first story, it is the most important element that builders can do to help things work better:

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“When leaving a message, please leave me a number that I can call you on in the evening, and how late I can return your call. I can cover a lot of calls in the evening. I often spend several hours between 7 and 12 pm answering questions in great detail.  You are always welcome to call 904 -529-0006 as late as you like. It only rings in the hangar, and it will not disturb us if you call late. About 1/2 the nights of the week I am in the hangar until midnight. If you ever ring the phone and it tells you the mail box is full, it is an electronic fluke caused by me not having call waiting, but also having some type of phone company complementary voice mail that I don’t want. This message just means I am on the line with a builder already.

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The absolute best way of contacting us: Send me a short email that looks like this:

“Subject:  Corvair engines, question from Bob Smith

Bob smith here: Please give me a call back on my house line 608-123-3456 or cell, 608-234-5467 any time up to 8pm CST. I have a number of questions about a Zenith 750. Thanks.”

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Jump Start Engines – part #6

Builders,

Three groups left to address in the closed case: The Case Group 1200, the Hub Group 2500, and the Rear Oil Case Group 2000.  Let’s take this in order and look at the case. At the bottom of this part I have included several paragraphs on cases from my note book on Corvair engines.  Worth printing and including in your conversion manual if you have not yet passed that part of the build process.

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If you are building a 2700, or a 2850, there is no machine work to be done to the case. It only needs to be cleaned really well, checked for damage, and have all the studs in it in good shape. If you would like a 3,000 cc engine, the six cylinder holes in the case have to be enlarged a bit on very good machinery. You can read about this by clicking on this story: 3,000cc Case Modifications.

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Below is the simple elements of the 1200 group. If you have a good core, you have nothing to buy, just a fair amount of time carefully cleaning:

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Case group (1200)

1201- Case -2 halves with studs-

1202- Main case bolts -8-

1203- Main case nuts -8-

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“Once you have an acceptable case, you need to clean and inspect it very well. Pressure wash it after soaking it with a cleaner like Simple Green. This will get most of the big stuff, but in the end, there is no substitute for several hours with plastic bristle brushes and careful scraping. Many people let their local transmission rebuilder give it a first pass at cleaning. The only two things you can’t do are use bead or sand blasting of any kind, nor use any type of scraper or abrasive on the parting surfaces of the crank cases.

The oil gallery plugs can be pulled with a ¼” drive extension. On 50% of engines these cannot be budged. Leave them in and use a gun cleaning kit to brush the galleries out from the end. Get a gun cleaning kit for a .17 caliber rifle, as these are the only size brush that fits in the oil feed holes to the main bearings. Check every oil passage. My neighbor lost a 200 HP Lycoming 2 hours after overhaul. $10K in damage was caused by a mud dauber insect making a sandy plug in an oil gallery. Check, don’t assume.

A lot of discussion goes on about what is acceptable for wear in a Corvair case. I know people who think that a bearing bore that is .0005” out of round makes a case scrap. I have good reason to say that this is an arbitrary number, not reflected in GM’s literature. For all we know they were not this good new. A much more reasonable idea is making sure the bearing bores are within a thousandth of an inch of being round. This can be directly checked with a bore gauge or a set of Ts and a good caliper. You can also evaluate this by looking at the plastigage when checking the crank.

The whole discussion seems like a lot of talk over a very little issue because I have never seen a spun bearing in a Corvair that had oil in it. If they had a big history of spun bearings and every fourth core had one, then bearing bores would be critical. In hundreds of cores I have not seen such an issue, so I am not alarmed. Same concept covers the cam bores and the lifter bores. Look carefully, clean carefully, but don’t let your project get derailed by an unreasonable arbitrary specification. In the first 30 years of Corvair powered flight, no one ever looked at these measurements, they just put engines together and went out and flew them. Over the years I have had a number of people say to me that they don’t want to build a Corvair after finding out that Corvairs don’t have cam bearings (the cam rides in the case). I pointed out to these people that Lycomings are the same way, and engines like the IO-360 use the bare aluminum case for the thrust bearing. I am sure they thought I was wrong or lying, but it is reality.

Some builders get off to a false start by deciding to pull the stock head studs out of the case because “they look rusty.” Do not do this. Studs with surface rust are very rarely damaged beyond use. Our FlyCorvair.net Web page has a good article about how to test head studs that you suspect of being weak. If a stud is very rusty on the top threads or shows signs of twisting or harsh tool marks, it is a good call to change it. If it just has surface rust, clean it off with Scotch-brite and repaint them. If you have questions on a specific stud, call me or send us pictures of it, and I will be glad to help you decide on a course of action.

The base of the studs is a special thread called a 3/8-NC5. It is not a 3/8-16 UNC thread.

Helicoils are 3/8-16 UNC. If you install a helicoil in a case, you must resize the end of the stud with a very sharp 3/8-16 die. Use real cutting oil if you expect this to work. Grab the body of the stud in a vise with soft jaws and clamp it very tight.

If you have a stock stud unscrew cleanly, without removing aluminum from the case, the hole and the stud can be carefully cleaned and dried off, and the stud then screwed back into place with Loctite 620 on it. 620 has awesome holding power. You must remember to put it on clean surfaces, and the bottle must be shaken thoroughly before applying. Keep in mind that half the holes are blind. If you fill one of these up with 620 and screw in the stud, it will hydraulically lock and stop. I drill the bottom of blind holes with a #60 drill to allow the pressure to escape. Do not chase a stock hole with a 3/8-16 tap; you’ll only ruin the threads. If you need to remove a stud or helicoil a hole, use the following method:

  1. Clean the cases thoroughly.

  2. Jam two 3/8-24 nuts into each other on end of stud.

  3. Heat case with propane torch. Put candle wax at base of stud when hot. (Capillary action will pull wax inside.)

  4. Unscrew stud.

  5. Drill cases on drill press for long helicoils. Follow directions that come with the helicoils.

  6. Clean studs with a wire brush; inspect for twisting or tool marks.

  7. Chase the 3/8-16 threads on studs with a split die. The threads on the studs have the NC-5 shape that must be chased with a standard 3/8-16 split die to ensure proper fit with the helicoils.

  8. Test fit into case. When satisfied, Loctite 620 into case.

I’ve often read that a #6 oversize Corvair stud fits in a helicoil. This is a bad joke; it does not. I recommend against using any of the oversize studs. They’re very difficult to screw into the case. They are also of varying quality. Clark’s also sells a 7/16-20 base stud. I would not recommend these, unless you absolutely have to use one. ARP made a batch of super high quality head studs. These cost $300 for a set of 24. They screw right into helicoils. Several of the engines we built and flew used these, including our own personal engine in our 601 and the engine we built for Rick Lindstroms’s 601. These were available in 2003-2005, but they are not made today.

As an alternative to using long helicoils, the case can have time-serts installed. These are available, along with installation kits, from Clark’s. Some people find these easier to install. Again, no stock or oversize stud will thread directly into a time-sert either. If you have a case with a lot of mangled studs, perhaps the easiest route is to find another case.

Always keep cases in pairs. If you change half the case, the motor should be considered junk. I’ve seen them run in cars this way, but it would be ludicrous to consider building a flight engine this way “

 

Jump Start Engines – part #5

Builders

In this part we look at the Camshaft Group 1100. You can refresh your thoughts on this by looking at the 2013 story I wrote about this group:

Getting Started in 2013, Part #3, The Camshaft Group (1100)

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The take away from that story is how the number system supports a wide array of choices available to builders, ranging from a reground cam  with a stock gear to a new cam with a fail safe billet gear installed for you.

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I have built and tested all of the options above, and they all work.  Which one should builders use? Well, any one that appeals to them after some reading to understand the differences. To amend this, let me share some of the additional things I have worked with in cams in the last few years.

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-The most popular cams in use in Corvairs remain the same Clark’s OT-10 (new and regrind) that we have been recommending for 15 years.

- I have built motors with and tested the California Corvairs CC-10 and it is a good quality cam and essentially the same output as the OT-10.

-I am having a run of cams ground to a pattern that we tested in 1997-98, based on a design done for me by the late Harvey Crane. The cam has a small advantage over an OT-10. The jump start engines will be built up with these cams. I had considered doing this before, but it took a while to find a US grinder who had the right experience and equipment and was OK with making cams for aircraft.

- I have worked with every Cam gear on the market, built engines around all of them, from the Clark’s basic gear through the $300 American Pi adjustable timing billet. I dislike the fact that the Clarks gears are likely Chinese products, but they do fit and work. The California Corvairs and Larry’s Billets are American made, but they are very tight fits on cams, and I do not recommend installing one at home. The California gear has a shallow key groove that requires the height of the key to be checked.

- Absolutely, under no circumstances, ever, hit a cam hear with a hammer to “finish install it”. This appears in Corvair car sites and is very poor advice. Cams are brittle, at the next College I will demonstrate how easy it is to crack or break one with a 16 oz. hammer.

-Here is a link to a seven and a half year old story from our main website: http://www.flycorvair.com/hangar1206a.html  Half way down, it is detailing how we put cam gears on. I note that I want the thrust washer on tight.  Below is a section from our webpage 14 moths later. When GM built your Corvair, it had a tight thrust washer. If you go on line, you can find a number of car people claim that they would prefer to have the washer loose. Although I can not pin point this as a failure issue, It is a good example of car people offering very poor advise.

If you press a cam gear on tight with an un-chamfered washer, the gear gets run out in it and is then junk.  It took many wrecked cam gears to spot why some Corvair parts sellers didn’t make the gear tight. It was the new washers made without the chamfer below that cause the gear not to sit properly if it was pressed all the way on. Their solution was to simply not put the gear on all the way and leave the washer loose. They had the washers fixed eventually, but in the last 24 months, this issue and un-chamfered washers have shown back up. There are pages of commentary on Corvair car sites about cam washer looseness, but not a single one of these notes anything about the root cause, the missing chamfer. Part of the reason why I am going to do a run of my own cams is because it is frustrating to solve this issue at my own expense years ago, but again see builders coming to colleges with cams with supplier installed gears that cost nearly $400 that again have loose washers.

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(Feb. 2008) “Technical News You Can Use
Above are two cam thrust washers for a Corvair. On the lathe, I’ve cut a slight bevel to provide clearance on the side of the washer that touches the cam. My research into building Corvair engines is continuous and ongoing. The unbeveled washer is an aftermarket part supplied by several of the Corvair parts houses. When pressing on a new cam gear, this will make the cam gear walk slightly out of square at the last moment. After years of installing countless cam gears without problem, we’d recently had trouble getting several of them to seat on their cams and hold tight their washers. Ignoring this problem, people selling cams with gears on had been leaving the washer loose as a really poor fix. It took a while to determine what was causing this issue, but a slight relief on the washer makes the difference.”

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Below, the Group 1100 chart from our webpage checklist:

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Cam group (1100)

1101- Cam

1102- Thrust washer

1103- Key

1104- Cam gear

1105- Hydraulic lifter set -12 total-

1106- Cam lubricant

1107- ZDDP oil additive

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Above, an engine being assembled at CC#22 in Texas. It is a Clarks Fail safe gear on an OT-10, and a Weseman Gen 1 bearing.  the dial indicator shows that the steel crankshaft hub that the Weseman bearing rides on is correctly installed. Barely visible are the three small Allen screws that are centered around the crank nub. By adjusting these screws and the tapered shims underneath them carefully, the steel crank hub can be zeroed to exact alignment with the crankshaft. This adjustment is not required on the Gen 2, as the bearing hub is installed on the crank in processing and ground concentric. The sole advantage of the Gen 1 is that it can be installed as a retrofit on a fully assembled engine. Most people building an engine with a 5th bearing from the start now opt for a Gen 2 bearing. More info at: http://flywithspa.com/fly5thbearingcom/5thbearingnewengine.html

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mmmmmmm

Jump Start Engines – part #4

Builders:

In this section, Lets look at two elements of the closed case, The Crank Group 1000 and the Weseman bearing Group 3000. There two parts make up the crank and 5th bearing arrangement, and are the fundamental components to the Jump Start Engines.

From background reading, you learned that the two places to have the stock GM 8409 crank processed are Moldex in MI and with Dan and Rachel Weseman in FL. There are a number of factors in which one you could choose, but my approach is to ask first: What 5th bearing are you using?

The most popular 5th bearing for Corvairs Is the Weseman Gen. 2. This is followed by their Gen. 1, and then Roy’s bearing. (The Jump Start Engines are being built around the Weseman Gen. 2 ) If you are going with a Gen. 2, then Dan and Rachel are going to process your crank in FL. If you are building a Gen.1 engine, you could go either way, but my preference is FL because the Dan replaces the gear on the crank with a new one and Moldex does not. (For builders interested in Roy bearings, Roy uses Moldex’s services, but he replaces the gear himself as part of his bearing design.)

You can take this link: http://flywithspa.com/corvaircomponents/new5thbearingcrankshaft.html directly to Dan and Rachel’s site for crankshaft rework information.  You can use this link to read about the Gen.2 5th bearing: http://flywithspa.com/fly5thbearingcom/5thbearingnewengine.html.  The total of these two parts is $2,200.

After we go all the way through this series and come up with exact totals for all the parts, assembly labor and the core, I am going to have all the builders interested in picking up a Jump Start Engine actually pay the $2,200 directly to the Wesemans as the ‘deposit’ on their engine. There are several reasons for this such as double record keeping, in state taxation, etc. But the most important one is that The four of us that I call “The Corvair all stars”, (Ourselves, the Wesemans, Roy’s Garage and Falcon Machine) have a long standing informal agreement that each company should get the regular price for his work, and the others support it, but don’t act as a paid dealer. There is a good reason for this. When a builder uses a part, he can rely on full support from not only us, but also the all star that made the specific part.  This has the effect of getting several experts into the builders corner, and incentivizing the others to show up at Corvair Colleges to directly work with builders. It is a cooperative relationship that primarily benefits the builders.

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Below are the numbers from the Group 1000:

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Crank group (1000)

1001(A)- Crank (8409 mark, GM)
1001(B)- Billet crank (Fly5thBearing.com)
1002- Crank gear
1003- Crank gear key
1004- Crank gear gasket
1005- Rear keys -2-
1006- Fuel pump eccentric
1007- Spacer
1008- Bronze distributor drive gear
1009- Oil slinger
1010- Main bearings
1011- Connecting rod bearings

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On the engine we will have 1001A cranks: the 1002 gear is replaced, along with 1003 and 1004; the two 1005 keys are #5858 from Clarks, 1006-1009 come on the core cranks, we just clean and inspect them carefully, but the ones on most core cranks are in good shape. We will be putting new main bearings, #1010 in the case when we assemble it.

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Weseman 5th bearing group (3000)

3001- Bearing kit (designed for short gold hub 2501B)
3002- Alteration to standard gold hub (2501A)
3003- Alteration to black hub (2501C)
NOTES: Selecting this bearing option allows deleting the 2300 group. Contact Dan Weseman directly at FlyWithSPA.com for more information.

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In a later part we will go over the 2501B hub, which is the correct one for the Weseman bearing, both Gen 2 and Gen 1. The two notes 3002 and 3003 relate to retrofitting a previously built engine with a Gen 1 bearing assembly. -ww.

 

 

Jump Start Engines – part#3

Builders,

In this part, let’s look at the sub-groups that will be in the assembled short block. One of the organizational tasks I put a huge amount to effort into in 2012-13 is our Group Numbering System, which logically breaks down your engine build into groups, and assigns every single part in the flight motor a number.

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When I wrote the getting started series, I introduced the numberings system with this story: Getting Started in 2013, Part #2, Group numbering system. It is a good, short, introduction, but I later changed the system slightly. In the first system (which was used in the getting started series) You had Group 1000, (the crank group) but you also had part# 1000 which was the crank. Shortly I saw this was a little ambiguous, and decided to make the crank part number 1001, and bump all the part numbers down one digit. Not a big deal, but it makes it easy to understand that when we are speaking of 1000, 1500 or 2000, we are speaking of the whole group, not an individual part. Our regular catalog page:

http://www.flycorvair.com/products.html

Has all the correct part numbers as they are after the revision. Read and understand the getting started articles, but the numbers we use in this series will be the final ones that appear on our catalog page.

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The catalog page has all groups, #1000 through #4300 on it. That may sound like a lot, but keep in mind that 3400 through 4300 deal with airframe installation components that you don’t need to get an engine running at a college. Also, there are a number of groups like the Front cover group 2300, that are deleted if you are building with a 5th bearing, There are two oil system groups, 2700 and the heavy duty 2800, and you only need one, and there are three 5th bearing groups, 3000 (Weseman), 3100 (Roy’s) and 3200 (mine) and you only need one. The numbering system has to cover a lot of options, but to build your engine you only need to use part of it. This series will guide you through with some examples.

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If you look at it for a minute, you will understand that the “Catalog page” is far more than a list of items for sale. only a small fraction of the part numbers are items we sell. The page has a larger function as a checklist for your engine build. Rather than flashing back to it, consider printing one out and getting a highlighter and checking the items off as you collect and prep them. Even though I have been building the engines for 25 years, I still like to use a checklist to get everything organized.

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I have a few hundred hours in Grace’s Taylorcraft. It is a very simple plane, but if you look in the glove box, it has a laminated, hand written pre-flight check list, and I still take it out and run through it and say the items aloud.  Make fun of that if you want, but I am never going to be the guy who took off with the fuel shut off, the plane radically out of trim, or the primer unlocked.  If you don’t want to be the guy who comes to a college to assemble and run his engine but doesn’t have lifters (#1105) or head gaskets. (#1403), use the checklist.

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OK, below are the Groups we will be dealing with to build the Jump Start closed cases.( Getting Started in 2013, Part #7, ‘Chas. Charlie’ Short Block ) after this we will break it down to the individual parts in each group.

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(1000) Crank group

(1100) Cam Group

(1200) Case Group

(2000) Rear oil case Group

(2400) Starter group

(2500) Hub Group

(3000) Weseman bearing Group

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Reading for background:

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To read about the Crank Group 1000

Getting Started in 2013, part #1, Crankshaft process options.

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To read about the Cam Group 1100:

Getting Started in 2013, Part #3, The Camshaft Group (1100)

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To read about the Case Group 1200:

Getting Started in 2013, Part #4, Case Group (1200)

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To read about the Rear oil case Group 2000:

High Volume Oil Pump

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“If two guys walk into my booth at an airshow and ask about engines, everyone should understand that I am going to be polite to the guy who wants to tell me about the 4 cylinder Corvair he had in high school, I am going to answer all the questions of the guy who has seen my website, but didn’t look enough to even hear about the number system, but I am going to invest as much of my time as possible with anyone who shows up with a printed numbers list, a highlighter, a pencil and a working knowledge of how we describe the engine now. There is only one of me, and there will be many people at an airshow as interested spectators. That’s good, but my mission is to teach builders, not entertain spectators. I am glad to talk to the later and do a little hangar flying if they are standing there, but mission #1 is to communicate with builders, and nothing says you’re a builder like having a written plan in your hand.” -ww

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( Our booth at Oshkosh 2014 is #616 across from Zenith aircraft)

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