New 3,000 cc Cleanex, Dale Williams, SC


Above, The Cleanex of Dale Williams taxis out at Corvair College #27. The story below was written 10 months before the photo.


Back in September my sister and I drove to NJ to see my parents.  Before leaving, I had spoken with Dan Weseman about Dale’s project. Because it’s a ‘Cleanex’ and a mechanical clone of Dan’s Wicked Cleanex, Dale had worked very closely with Dan on the engine installation. Because I was going to pass within 80 miles of Dales’ place I offered to divert to make a house call on my way back from NJ.

Dan had assembled Dales’ engine for him previously, long before his airframe was complete. When he was later doing ground tests the engine exhibited a slight miss. A quick investigation revealed that the engine had broken a rocker stud, and was actually only running on 5 cylinders. To give you an idea of how rare an event this is, in 24 years of working with Corvairs I had only ever seen it happen once before. Because of the Corvairs smoothness, it was not readily apparent that it was only making 5/6 ths of its power. A less observant operator might have flown it that way, and it was certainly making enough power to take off.

After confirming the issue in the house call, I picked up the engine at Dan’s request to return it to him in Florida. Dan takes standing behind anything he touches very seriously, and he told Dale that he would replace all the rocker studs with brand new ones and test run the motor on our stand at no charge. Dan also used the time to upgrade the engine with exhaust valve rotators.

 You find out what people are like when there is an issue, not when things are perfect. This works both ways; Dan insisting that he correct the issue and Dale being very understanding about it. The task was done shortly, and as you can read below, Dale is very happy with the outcome.

Funny note: Just to show you that all airports have a self-appointed ‘engine expert’, read Dales letter. When we were having a very peaceful time in Dale’s hangar, the local expert pulled up and Dale knew that quick thinking would avoid a long lecture from this guy on the evils of Corvairs. Dale just introduced me as his brother from out-of-town, and the expert was soon on his way.

Hats off to Dale Williams, builder of the “Daughter of Cleanex” N-319WF.


I can verify that you do make house calls and on short notice! It was September 3rd, 2012 while on vacation that you came by St. George Airport (6J2) to pick up my 3.0 Corvair and take it to Dan for some repair/upgrade work. We spent a few hours talking in the hangar and when the local “VW engine expert” (a.k.a. “all” engine expert) drove up I introduced you as my brother so that we could be saved the time of him giving us lessons of why the Corvair was a bad idea for my Cleanex.

I want to thank you for what you did for me and commend you for giving such great service with a personal touch. Dan had the work to my engine done quickly and I have since installed it and the Cleanex I call “Myunn” now has nearly 20 hours on it. What a combination this air frame and engine make! Smooth and powerful with the sound of “authority” (pun intended) roaring out of those WW straight pipes.

I had mentioned in another reply about the “rolled on” painting process I used. It was the same one Clarence Dunkerley used on his Cleanex. Here is the nearly final result:

Thanks again William. You truly may never know how much you have changed the experimental aircraft industry for the better!

Dale Williams
N319WF @ 6J2
Myunn a.k.a. “Daughter of Cleanex”

Mail Sack, 2/20/13, Kitfox, Panther, Colleges.


Here is a sample of the latest letters:

On the Panther engine run:

Builder Harold Bickford writes:

“Hi William, I expect also that someone will say that a 62″ prop and 2.520 rpm shows that the Corvair can’t turn much of a prop or something along those lines. Clearly any propeller driven airplane and engine for a particular flight profile will have an optimum prop. In the case of the Pietenpol climb performance in a draggy airframe means a different prop than Dan wants for the Panther. With the Piet/Corvair combination there is an experience base to draw from with real world results by folks who’ve done the work. That trumps the “I heard that….” type of commentary which is all too common. With the Panther, Dan and you are pushing the envelope in a different direction and adding to that real world data base. The fact that conventional wisdom is replaced with actual test and performance data is the critical difference. Build, learn fly; what could be better? Harold”

Harold, When people talk about pitch and diameter, they often forget to consider blade area which varies a lot from design to design. It would be like comparing aircraft stall speeds by just looking at wing span and angle of attack, but not taking wing area into consideration. This particular prop design had a fair amount of blade area. Also HP absorption on props is not linear, its exponential. An engine putting away 90 hp at 2800 rpm will only need a prop 1/4 the size of one absorbing 90 hp at 1400 rpm.-ww 

Pietenpol builder Dave Aldrich writes:

“Under the “philosophy” section of this post, you could add the Lycoming/Continental (NOT Lycosaurus, an inappropriate and inaccurate term) engines that are used on many of the new homebuilts of today, even though some are almost as old as your box and pan brake. Sometimes the simplicity and elegance of a design doesn’t need “major innovation”.

Since you bring up the subject of firearms, in my gun safe are a 1903 Springfield 30-06 (as built, though the leather sling has seen better days), a 1930′s Stevens single shot lever-action .22 (the stock is a bit loose from an encounter with an irate goat on the family farm in Indiana) and an LC Smith side-by-side 20 gauge, also from the same time frame. All 3 still function perfectly. The sad part is that none of my sons have any interest in them so at some point I’ll sell them to some one who appreciates history and quality. Given the mood of the politicians, I may have to do that soon lest it be forbidden… Sic transit gloria mundi.”

Dave, friends who have been to our place recognize that the truck in the photo is sitting on the half of our yard with a big backstop that forms our 25 yard pistol/plinking range. We are lucky to live in a rural setting, and there is nothing behind our house for several miles. The range is a neighborhood resource here. While I am concerned about firearms issues, I remain optimistic, thinking of the example of how our extreme freedom to build any kind of aircraft we like in this country has remained in place through a number of challenges. Perhaps most people understand that when we walk away from individual choice and personal responsibility, we are walking away from the defining characteristic of being an American.-ww

Builder Chris Craver writes:

“Great video William. Love it!”

Zenith 601XL Builder and Flyer Andy Elliott writes:

“My 3100-powered, highly cleaned-up 601XLb taildragger runs a 64×47 Sensenich. It butts up against the LSA limits down low at 3250 rpm (sucking gas like crazy!), and will cruise at 115 KTAS up high (say 10500) at 3050 at WOT, just under 5 GPH.
Static rpm is ~2700 depending on the conditions, which is a little on the low side, but since the plane gets off the ground in ~1000′, and as I only use 100LL and am careful about adding throttle smoothly during takeoff at low altitudes, I think it’s a pretty good cruise prop. Even so, at full throttle on the ground, I can lift the tail with the brakes locked.
I have flown in and out of a number of paved airports at >9000′ DA, and the performance has been “acceptable” as long as I keep the plane at 90 KIAS in the climb, which usually yields about 2800 rpm. Andy”


On the subject of Kitfox mounts:

Builder “PJ” writes:

“Great pictures of Vern welding. I just took the EAA Workshop Gas Welding class last week in Chesapeake VA. Cost me $329 for the 2 day class. It was a challenge learning to use the torch. We had 12 guys in a very small room with very hot torches and its amazing nobody set their eyebrows or beards on fire!”


On the topic of upcoming Colleges:

Zenith builder Bill Mills writes:

“William, I just purchased a 1966 engine to convert for the Zenith 650 that I am scratch building. Started to disassemble, taking my time. Dan’s engine sounds great. Looking forward to college #25. Will you be confirming it soon? So much to learn about the conversion.
Bill Mills EAA chapter 282 Clearwater, FL”

Builder Gary McMullen writes:

“How do I register for the College before Sun n Fun and what are the cost? This would be for information and learning so that myself and another individual will be able to use Corvair engines in our homebuilts.”

Bill and Gary, I will have more info on CC#25 in the next day or two, Arnold is getting us motel info right now (we will also have free camping on site.) The College is free, but we may have a modest registration fee to give Arnold a small budget to cover tables and port a johns to supplement the regular women’s room in the hangar. We are planning on having EAA chapter #534 be on hand to provide all the food a la carte for modest cost. More info here in the next day or so.-ww

Zenith builders Craig and Val Westedt write:

“William I’m glad to see that you are going to Sun and Fun again this year. I wish Val and I could make it there too. Other commitments prevent us from doing so. I know that preparing for that event and CC25 will be taking up your time and plans but I would like to request a little of your time to indicate your thoughts on whether you want to have a college in Oklahoma. Our EAA chapter 1040 here in Cookson has set aside time the week after the Zenith open house for an event if you so desire. Thanks for your consideration, Craig ”

Builders, Although I have already spoken with Crag about this, and we came to the conclusion that it would be biting off more than we have the time budget for this year, I would like every one to see that we have people like Craig and Val, who after attending a College were inspired to ‘give back’ by going out of their way to offer to host an event with their EAA chapter. It is a good indication of the quality of people we attract to the Corvair movement. I have found plenty of “What’s in it for me?” types in other settings in aviation, but that is not the perspective nor the personal philosophy of Corvair builders. I told Craig that I would like to at least include their place as a stop on the “Corvair Air Tour” we have been trying to plan for the same time frame in September.-ww

Builder Tim Wall writes:

“William, Whats the possible date for CC at Chino? Tim”

Tim, we are still working on the Chino dates. 90% of the behind the scenes people working on the Chino event have voted for the middle of May. We will have more info here as we get it together.-ww

Corvair House Call, Range: 335 miles.


Over the years I have done something several hundred times that other aviation businesses don’t: I made a house call. Our primary work is educational, and the hardware sales support that mission. This difference has many ramifications, but one of them is that we take the time to meet builders whenever there is an opportunity to advance an individual’s knowledge and project.

Last week I was headed to Columbia, S.C., to help my sister move. Technically this wasn’t a true house call because I only made it 335 out of the 400 miles to York, S.C., where builders Michael Durbin and Stefan N-Plotnicki are getting started on their Zenith 650 kit. I spoke with them on the phone and Michael suggested that they would be glad to load up their Corvair on a stand in the back of Stefan’s pick up and meet me at my sister’s place for an evening “house call.” This offer of meeting me part way and their enthusiasm for their project set the tone for a productive visit.


Above photo taken in my sister’s driveway. Note Corvair on stand in the back of the truck. Stefan on the left and Michael on the right are brothers-in-law and partners in a Corvair powered Zenith 650 project. Their wives are sisters. Michael has long been involved in aviation and served as a mechanic in the USAF.  Stefan has a lot of mechanical experience on different engines. He is a proud native of Poland. “Na zdrowie!”


Michael and Stefan purchased their project from the family of a builder who was sadly killed in an auto accident. The builder had done some work on the engine to clean it up and put it on a stand, but had done no work to the airframe kit. Initially the original builder was thinking of putting the Corvair on a plans built wooden kit, but later opted to purchase the 650 kit. These guys suspected that the engine they have is basically a good core, and my inspection proved them correct. The view above shows that the engine was very clean, but was not actually rebuilt. The rod bolts in the picture are used stock ones and the piston skirts show that the pistons are cast. Many years ago I had a difficult time convincing some builders to put quality parts in their engines. Very rarely do we see stuff like this any more. Michael and Stefan plan on a first class rebuild and are only planning on using this engine as a very clean core.


The above photo shows that the pistons are not just cast, but they were also used. Some builders who had been in the EAA a long time had heard that Pietenpol builders in the 1970s had flown Corvairs directly removed from cars with some success. This is true, but I have never encouraged people to do this. We ask much more output from engines now, and for reasons outlined in my Manual, I would actually trust a 25,000 mile stock car engine over the above engine. Re-torquing original rod bolts and using thicker base gaskets on an engine with previously rigid cylinders would actually make the above engine less reliable than one just pulled from a running car. Either way, the point is academic, because no one is planning on flying either of those concepts today.


Above: Home-made  4″ deep sump pan fabricated by original guy. The rough areas are partially ground down welds. The cut outs in the pan lip for the mounts would leak like a sieve. This builder was not following mine nor Bernard Pietenpol’s notes. Both of us told people not to cut the pan like that. Ideas like the one above show that the original builder was willing to put in time, but was not willing to follow known information. The original builder actually had one of our Conversion Manuals. Ideas like this were once common on the Internet, promoted by people who had never built a Corvair themselves.


Above, the project is now in the hands of two very positive builders who are aiming for an outstanding aircraft and engine within a reasonable budget. Their previous mechanical and aircraft experience guides them to a much better quality and far more proven path than the first builder was charting. The above photo was taken after we got to spend two hours going over details and fine tuning a build plan that was tailored to their budget and timeline, and also meets their personal goals of becoming experts on their own engine. In their hands are a number of the parts that they picked up from me that evening. Michael is also holding his Zenith 650 plans set. He brought it to ask me if the Corvair required any airframe changes or alterations to the Zenith fuel system. I pointed out that one of our original design goals with our first Zenith 10 years ago was to make no changes behind the firewall whatsoever. If a picture is worth a thousand words, this one says that much about their positive attitude. Look for these two to have an engine running at a College by the end of the year, and a flying plane next season. Good goals, but just physical manifestations of the real achievement, becoming a proven aviation craftsman and an expert in both your airframe and powerplant. -ww