William Wynne

"The Corvair Authority"
P.O. Box 290802
Port Orange, FL 32129-0802
(386) 451-3676


New & Improved Exhaust Stubs and Clamps for Corvair Conversion

Get a quick start on building your own exhaust system with the Exhaust Stubs and Clamps kit, Part No. EX-1. These Exhaust Stubs are precision made to clamp onto the existing steel stack from the Corvair cylinder head. The six Clamps allow you to utilize the stock Corvair exhaust doughnuts and have an easily removable exhaust system, which, when bolted in place, has a great deal of rigidity and seals tight.

The Clamps and flanges are precision CNC machined, and feature machined gasket surfaces. The Exhaust Stack is a swedged 4130 tube tig welded to the flange. From these six Stacks, any exhaust system can be made. They are equally useful as a beginning point for straight stacks or a complete exhaust system.

The $159 price includes the six Exhaust Stubs, six Clamps, instructions (reprinted below) and shipping in the U.S. I accept payment by check or money order in U.S. dollars payable to William Wynne, P.O. Box 290802, Port Orange, FL 32129-0802, or credit cards via PayPal by clicking below:

For international orders, including Canada, please add $15 for S&H by clicking below:

Please print, complete and return a Liability Statement with all orders. These are available for printing at the Liability Statement Page.

Thank you for your order. Your support makes possible further research and development on the Corvair.

Installation Instructions for Exhaust Stubs and Clamps

Thank you for buying a set of Exhaust Stubs and Clamps, Part No. EX-1. Your purchase makes possible my further research and development on the Corvair. In this way, you’re investing in the future development and perfection of your chosen motor.

These notes are supplementary to my most current Conversion Manual. These Exhaust Stubs and Clamps are developed as part of the system that we use to convert aircraft motors. This system is outlined in the Conversion Manual. The parts alone, without the information contained in the Manual, will not allow you to develop as reliable an aircraft conversion. When I develop and market a part, it is fully flight tested, and designed to work in concert with the other parts in the conversion. I take into account the way that most people are capable of installing and operating the part. There’s a great deal of consideration that goes into these issues, and I urge you to utilize all the information in the Manual and the parts in the way that they are intended to be used. Of course, contact me at any time with any question you may have.

To be fair, everyone needs to understand that these are not certified parts, and it's not a certified motor. Experimental is not a misnomer; everything we do in this field is of increased risk. If anyone even suspects that they have a problem, E-MAIL or CALL ME. If you have never worked with torque wrenches and precision fasteners, get help from an A&P. Let's all remember to use our heads and not take unnecessary risks. I have gone to great lengths to make these components as reliable and easy to install as possible within the bounds of affordability. I have personally flown all of these parts, because I have a low opinion of people who market aircraft parts without flying the parts themselves. I believe that each and every part I sell is the best solution to its respective aspect of converting a Corvair engine. Take your time and do good work. The system is proven and will reward you with the same type of reliable flight performance we have always had.

My R&D work during the past years has shown this to be a difficult part for homebuilders to fabricate. In response, I have taken the time to develop, test and fly this product. The intention is to give you, the builder, a running start at fabricating a good tubular exhaust for your specific aircraft.

It is assumed that everyone purchasing a set of these parts has an up-to-date Conversion Manual, the 2002 edition. The Manual includes many pages of detailed information on exhaust systems and welding applicable to constructing your own system.

These Stubs are sized to fit over the stock exhaust stack in 95 and 110hp heads. The Clamp functions like a distributor clamp to hold the stack in place. Testing has proven that this system will easily hold a 3 pound exhaust header and tailpipe to the Corvair cylinder head. If your exhaust system is heavier than this, or longer, you may want to investigate another type of brace further downstream in the exhaust system. Remember, the brace will have to be rigid to the engine, not the motor mount or airframe.

The stock exhaust doughnuts are used with this kit. I have had best results by flat spotting the face of the doughnut, which will contact my exhaust stack. Leave the other side of the doughnut its stock shape that is intended to mate with the GM exhaust stack in the head.

You should use a stainless split lock washer and a stainless 3/8"-16 self-locking, all metal nut to hold down the Clamp. If the corners of the Clamp contact the weld bead on the stack, you may file them slightly in order to ensure the contact point is on the welded ring and not the bead. It has not proven crucial, but it is better practice to have the Clamp contact the ring.

When you weld your exhaust system, avoid using excessive heat. Too much heat will cause shrinkage in the header, and then the header will not fit. Minor adjustments in the fit can be made by lightly tapping the stock exhaust stack with a small hammer. Most stacks will move slightly in the head sideways.

Exhaust systems I have built are made of 1 ˝" diameter tubing. All three pipes on each head flow out through a single pipe. While this may seem small, testing reveals that it offers no restriction to power. Keep in mind that only one exhaust valve is open at a time in each cylinder head. If you build a carb heat muff, make it out of light gauge stainless and attach it to the header with stainless steel pop rivets through welded on tabs.

All airplanes should have carbon monoxide detectors in the cabin, and no one should consider cabin heat without using one. Many people in aviation have been impaired by carbon monoxide. Do not let yourself be added to this list.

Try to make your exhaust pipes point backward at least at a 45 degree angle. Straight-down exhaust systems create a lot of drag in cruise flight. Exhaust systems can be painted with ceramic paint or preferably ceramic coated. Mild steel exhaust systems last a long time with just a little care.

When done, inspect your exhaust system frequently for tightness, integrity, welds, etc. In the initial phases of flight testing, it's something I check before every flight.

Happy building and feel free to e-mail or call with any questions you may have. Your beautiful and reliable exhaust system will be a tribute to you, the airplane builder.

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