William Wynne

"The Corvair Authority"
5000-18 HWY 17 #247
Orange Park, FL 32003


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December 22, 2004

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Subj: Which spinner?
Date: 12/21/04

I see three different 13-inch spinners for sale by Van's: ones for wood, Sensenich, and variable-pitch props. Which one do you have for your Warp Drive prop? I notice that the one shown on the Web page had no slots in it in the early stages.

Steve Mineart, #5833, CH601XL, Iowa

Reply from WW:
The Van's spinner we use is Part No. FP-13. This is the standard spinner we're going to use on virtually all of our installations. Our Front Bulkhead and Crushplate Assembly allows the use of the comparatively thin Warp Drive prop with this deep spinner. We're currently working on an elaborate jig which will allow us to match drill the spinner to the bulkheads for you. This will save the first-time aircraft builder from the time consuming task of getting the spinner perfectly true. We're shooting to have this tool done by the end of January. We'll show it with pictures on www.FlyCorvair.com as soon as it's finished.

Subj: Carter YH Carb
Date: 12/21/04

You answered a lot of questions about carbs in the past, both in the Manual and on your Web site. I wonder if you have ever tried using the Carter YH side-draft carb that comes on the 180 turbo Corvairs? Seems like it might be a natural fit if you don't plan to use a mixture control. I personally have already acquired an MA-3SPA that I plan to use, but I have always wondered about the Carter YH.

Thanks, Dave Morris, Dragonfly, Texas
Reply from WW:
You think like Bernie Pietenpol. If you read Bernie Pietenpol's notes from his experiments in the 1960s, he mentions using what he calls a Spider carburetor, which Corvair car people know as a YH off an early model turbo engine. He noted that it was heavy, and prone to icing, an assessment which holds true today. YH is also the original carb from early 6-cylinder Corvettes. If you check out the overhaul price, it's actually more expensive than many aircraft carburetors. It also has many cast iron parts, which make it heavy and potentially damaged by corrosion.

Subj: Oil Pans
Date: 12/21/04

I received the oil pan today. It looks great. Thank you. What was the new method of attachment so as not to have to safety wire the bolts around the pan?? You had told me when I was there, but I did not write it down. Thanks--

Joe Horton, KR-2, Coopersburg, Pa.
Reply from WW:
The most popular companion piece to our Light Weight, Deep Sump Oil Pan is the Oil Pan Installation Kit. It contains all the fasteners, a modified oil pickup to reach to the bottom of the pan, a drain plug, and instructions. These kits come two ways: One is with drilled head stainless Allens which you safety wire after installation, and the second is with steel studs, which you Loctite into the case and use with all metal AN locknuts. We charge $49 for the Install Kit. We'll send the Kit with either hardware if the customer has a preference. Shortly, we'll integrate both into a single, complete kit. But they appear currently as two separate parts at The FlyCorvair.com Online Catalog because the Oil Pan's introduction pre-dates the hardware kit by several months.

Subj: Starter Ring Gear Change
Date: 12/21/04

My manual (#5597) recommends a Nissan Sentra 10-1/2" ring gear. I'm assuming the stock Subaru starter will mate to this and turn the ring gear. Recently I have seen that you are now recommending the Ford Taurus ring gear and changing out the starter gear. My question is, what will I be sacrificing if I choose to use the stock starter gear and the Nissan Sentra ring gear that I purchased when I first received my mMnual from you a year and a half ago? Thank you for your help in this matter,

Scott Laughlin, Manual #5597, Omaha, Nebraska, 601XL/Corvair, 75% complete
Reply from WW:
The Nissan arrangement is a perfectly good setup, and is flying on a number of our customers' airplanes. We went with the Ford because they're about a pound lighter, and far more available. We buy them by the dozen, whereas the Nissan had hit or miss availability. If you have the Nissan gear, go with it. It's not a big issue. But everyone who's yet to pick one up should use the Ford.

Subj: Jabiru J250
Date: 12/22/04

It appears that the Jabiru J250 would meet our needs but I still believe that the Corvair is the best engine for me. Have you any experience with Jabiru airplanes? Thoughts on the match? Considering developing mount and related items for installation? It could easily handle the weight and seems appropriate in HP. Thanks in advance,

Tom Kelso

P.S. I have the Manual and too many cores along with too many cars.

Reply from WW:
One can never have too many cores or too many cars. We keep six Corvairs at the hangar. I have one, Gus has one, and Kevin has four. Additionally, Kevin has one at home, and has a van awaiting pickup in California. You two would get along great.

Few people know that Jabiru has a line of aircraft in addition to their engines. It would be very ironic indeed to have a Corvair motor on a Jabiru airframe instead of the obvious Jabiru engine. This appeals to our sense of humor. If you buy the airframe, we'll make you a custom motor mount. Our friend Gary Coppen owns the Corvair/Skycoupe. The Skycoupe is designed by Ray Stits of Stits covering fame. Gary has to be the only guy in the world who covered his Skycoupe in Seconite. He always jokes about getting a photo of Ray Stits standing in front of the Skycoupe. It's the same kind of humor considering a Corvair powered Jabiru airframe.

Subj: Valve Seat, Distributor Clip
Date: 12/22/04

I have a couple questions. I'm not building presently but have three engines (1 disassembled). One of my engines pulled the valve seat out and had been run enough to considerably enlarge the hole (about 1/4 inch). Do you think this can be realiably welded and remachined?

The other is that I found a round metal clip in the oil pan. The only place I can think where it may have come from is around the distributor shaft. It was not distorted or cut up so apparently it has done no damage. This might be a safety item that all Corvair builders should look at on how to prevent. If that piece lodged in the distributor gear, it would certainly bring you out of the air. Thanks,

Ray Simpkins, Piketon, OH, Manual #5389
Reply from WW:
Corvair heads are cheap and plentiful enough that I'd advise you to simply find another matching head. It need not have identical numbers. Just keep 110 heads with each other, and 95 heads with each other. And of course, you'll need to ensure you have a 1964 or 1965-69 cylinder head, whichever your cylinders require. While I'm sure the right welder could weld up the combustion chamber, I myself have found it difficult to do welded repairs in the combustion chamber because of the extreme difficulty cleaning the aluminum of contaminants. I restrict our welding on heads to intake pipes and cylinder fin repair. In both these cases, we're working from clean, machined surfaces, which weld nicely. It's hard to imagine a good repair costing less than another core cylinder head. Perhaps one of your other engines has better heads.

The clip down the distributor hole, if it's basically a washer with two bent corners, is part of the distributor hold down clamp. People did occasionally drop these down the hole and not bother to fish them out with a magnet. You're right that you cannot tolerate any type of fastener dropped into the motor at all. There are round, machine shims on the distributor shaft, but I've never seen a broken one in the hundreds of distributors we've handled.

Subj: Open
Date: 12/20/04

Hi William. Finished my RV9A tail, soon to be for sale. I picked up a great Corvair engine last week. New plan is to build a 601XL.

Steve Gordon, Cincinnati, Ohio, Manual #6267

Reply from WW:
An RV-9 is certainly a good aircraft, but the 601 fills the bill for many people. Beyond being a candidate for a Corvair engine, which the RV9 is not, the 601 is much faster to build, perhaps taking only a third the time. My EAA chapter, 288, has an extraordinary following of RVs, and many of these people studied our 601 closely when we first picked it up. Most of them were very impressed that we completed and flew the airplane in a fraction of a year, something anyone would be very hard presssed to do with an RV.

Subj: Open
Date: 12/21/04

Just purchased an "RD" engine this weekend. It's being torn down and inspected after the first of the year.

Robert Johnsen, Nampa, Idaho (Canyon County), Zenith 601XL, Manual #6434

Reply from WW:
Congratulations on your find. An RD is a very common Corvair, and an excellent candidate for conversion. The first Corvair I owned was a 1967 coupe. I drove it for many years as my only car. This included trips to California through Death Valley, as well as throughout the northeast. This car was equipped with an RD engine. When the body finally gave its last full measure, I saved the engine to rebuild it for something special. Today, this exact engine case is the one that is in our 601. I'm sure your engine will provide you with as many enjoyable adventures.

Subj: 601 Performance
Date: 12/20/04

Thank you for opening up the Q&A again. This is a welcome addition.

Im still very curious what real performance numbers as far as cruise and WOT you are getting on your Corvair powered 601XL. Ive shied away from building the 601XL mostly because of the historic lack of accurate performance numbers from the Zenith Web site, and Ive been anxiously awaiting your figures because I know they will be the most accurate available with probably the cleanest build out there. I have a hard time taking the Zenith published numbers to heart, since Ive read many a posting from 601HD builders claiming only 85knots max cruise, while the Zenith Web site shows it should cruise at 120mph.

Im still exploring my options between building a Sonex and building a 601XL. Id like to power my plane with a Corvair, but I consider the Sonex a less than proven candidate for Corvair power based on only the 1 example flying and, of course, your lengthy advice on the subject, Id likely choose something else for the Sonex. Unless I see that someone is getting decent speed from the 601XL, it would be a tough choice to make.

So, have you done triangulated speed tests on the 601 Vair??? If so can you publish the results here?? Are you waiting for some modifications first???

Thanks, Bruce Johnson, San Antonio, TX

Reply from WW:
The last aerodynamic modifications I want to make to the 601 are coming together. I stil want to get wheelpants and gearleg fairings on it, and we're contemplating a smaller tailwheel. From previous experience, I suspect there's 8 or 9 mph in these changes. We flew the 601 this morning (Dec. 22) for the first time with the smaller 15x600x6 tires. The plane picked up 4 mph. We chose these because they'll fit inside RV-8 wheelpants. We changed the landing gear leg last week, and prior to this, I didn't want to build gear leg fairings for a gear we were planning on changing. The plane flew at 133-134 mph indicated at 24" of MAP and 3000rpm. This is a cruise power setting that burns about 5gph. Top speed is about 10 mph faster. I hope to have the gear legs faired and the wheel pants on by mid January. While our cowl may be slightly more streamlined, our airplane is about the same level of finish as the factory plane. I actually think the smaller wheels and fairings would make the tricycle gear model slightly faster on the same engine.

Our intention is to finish the mods and let everybody know where it stands. We're very happy with the way the plane flys. We're going to run the plane in the Sun 100 Air Race (a triangular 100 mile course) this coming April at Sun 'N Fun. The published results of the race end all debate of what particular aircraft are capable of. You can look up past results in old copies of Sport Aviation. Some kit planes noted for high speeds in brochures are noticably absent from the stats. For example, Europa Aircraft, which claims 200mph capability, have to my knowledge never run the race. They could hardly claim it's inconvenient since they're based at the Sun 'N Fun airport. You can come to your own conclusions. Whatever our speed shows in the race, people will certainly know it's an honest number.

When comparing 601s, you've got to remember that an HD is a radically different wing than an XL. Even the HDS, billed as a faster wing than an HD, is not as aerodynamic as the XL. As a side benefit, the XL with flaps lands slower than either the HD or HDS. I too read reports of HDs that cruised below factory advertised numbers. However, many of these reports failed to include details about whether the plane was plans built or built from a kit, what kind of engine and how healthy it was, whether it had a good prop or a homemade one, and what kind of cowling, wheelpants and leg fairings it had. With these points in mind, I don't think that the factory published numbers are that far fetched. We've flown more than 25 people in our 601, and if you're in our area, we'll be glad to take you for a ride and demonstrate why we're enthusiastic about the design.

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