Delays delays ...

I've got to sit tight on the engine rebuild and am waiting for more spare time. I've got a baby, after all. Have had for five and a half months. So, engines and CH 750 get to wait.

Disassembly Complete

Today I finished up disassembly of the Corvair motor. Here's a last picture:




Now I'm going to have to clean it all up!

Case, Crankshaft, and Cam ...

Is all that is left. Here is how it went:

Note that one of the cylinders came off with the head. I have already removed its piston / connecting rod in this photo. It took a bit of giggling and some slight hammer taps on the cylinder tabs to loosen it from the head. I did not BANG on it. Instead I tapped back and forth, rotationally, spraying lots of penetrating oil and letting it sit between workings. Eventually it pulled off. The trick here is patience. If you BANG, you'll likely destroy.

Also in the pic above one of the cylinders and pistons are locked together. The cylinder / piston have pulled off of the case by rotating the crankshaft. I never used any significant force. Rather, I followed the good advice in Richard Finch's "How to Keep Your Corvair Alive": very small movements back and forth, with lots of lubricant and take plenty of time. When it moves just a tiny amount, you've won the day. It will come apart in due time.

Next off: the bell housing. That came off easy leaving this last bit:

Taking the last two

Cylinders off today. Pics to follow ...

8409

Ahh ... that is the number you want to see on your crankshaft, and I got to see it today after getting the heads off and unsticking my motor. At first all I could see was the stamp "14A" and that was not what I was looking for.

Tomorrow I should be able to complete removing the last two cylinders.

Then I'll write about unsticking a Corvair motor. Even though GM manufactured something like 1.8 million of them, they are getting harder to find. William Wynne recommends paying a little more for a motor that rotates easily before you disassemble it. I couldn't find one of those. But I did get motor #1 taken apart, and the crank is now turning enough to get all the connecting rods and cylinders off. More on how to do that, and some encouragement, later on.

Pushrod Tube Removal

You have to remove the pushrod tubes before taking the heads off.

In order to prevent dinging the tubes up or ruining them with pliers, you use a special tool, some people make their own with a piece of thin wall 7/8 inch tubing and a bolt, William Wynne demonstates one he made in his disassemby video. I could have made one like that but it would have taken more time to get the welding gear out, go get gas, practice up again, etc etc, so I ordered one from Clark's Corvairs. The head piece of 7/8 rotates, so it's better than one I would have made and I can tell you that the rotating aspect makes it much easier to use than a welded one because you can work it around the exahust manifold tubes and the bottom of the case easier. Here's a picture:

Special Tools

There're a couple of specialty tools that I decided to order; both I could have made had my workspace been a bit better and if I'd had all my tools together: a gear puller and a pushrod tube remover.

Instead I ordered them from Clark's Corvairs. Of course I might have made a gear puller from an automotive parts place or Sears work, but they actually cost more than the harmonic balancer puller. Later I can make a general gear puller from the one I'm getting from Clark's.

Unfortunately the tools won't be here until Monday and I can't make much more disassembly progress until they get here.

Cylinder Head Nuts and Block Studs

Today I removed the nuts on the upper engine block studs and removed the rocker arm studs from the lower engine block studs. Everything came off without trouble except for the upper #3 nut/stud on the left hand side of the motor (looking down on it from the harmonic balancer pulley end).

The end threads on that upper stud were so rusted together that there was no way for it to be cleaned and reused, let alone remove the nut. I wound up unscrewing the engine stud itself, which did not strip or twist. There is a small chance I guess it could be reconditioned, but I have my doubts. The availability of the upper studs may represent a problem.

It's an obstacle which I will overcome.

Engine Type

The block number:
T1216RK

This translates to a powerglide, high performance Corvair with air conditioning. The engine was manufactured at the Tonawanda, NY plant on the 16th of December 1965.

The head number:
3856759

This is 110 HP head.

Crank number:
I can't yet freely rotate the motor so I am not sure about the crank ID number yet.

Slow Weekend

I've been slowly and methodically taking apart a Corvair engine. I have removed sheet metal, exhaust manifolds, header covers, rocker arms, pushrods, and the magnesium fan blower and top crankcase cover. Here's what the engine looks like now:









My advice for parts removal is to clean them superficially with WD40, dry them, and put them in small zip locked bags labeled and grouped according to function. I also marked the engine serial number on the bag because I have 3 cores. Throwing all the nuts / bolts / washers into one big bag or into a box will be regrettable weeks or months later as you scratch your head trying to figure out what went where.

I'm deviating from the order shown in William Wynne's disassembly DVD for a few reasons:


1) I need to buy a set of deep set 6 point sockets for removing the rocker arm head studs and the outside head stud nuts.
2) I don't have the special tool to knock out the push rod tubes yet.
3) I haven't bought a gear puller for the harmonic balancer yet.


There's another reason: This engine is partially siezed. I may wind up removing some of the cylinders and pistons and then proceeding to try and rotate it without damaging it. I have seen one builder recommending electrolysis for removing rust from siezed piston/cylinders and it seems to have worked for him. I may try that rather than banging things.


Now, for that puller and socket set.

This and That

This site is all about documenting how to turn this:

Into that:

(see Mark Langford)

And documenting how to turn this:

Into that:

(see Zenith Aircraft Company)

Why Corvair?

The first documented flying done with a Corvair motor modified for flight was in 1960. A guy named Bernie Pietenpol, who designed small aircraft for himself and other homebuilders, mounted one on a Cub, and then on a plane he had designed and built called "The Air Camper".

Corvair engine cores are getting a bit hard to find, but I picked up three recently. Two for $75 and one for $50. So, for $200 I have the core parts for three air-cooled, 100HP flight engines. True, they will be completely rebuilt before they can be mounted to the front of a small aircraft and expected to deliver safe and reliable flight. The main parts these cores provide are the case, the crankshaft, the cylinders, and the heads. Pretty much everything else gets replaced.

In "How to Keep Your Corvair Alive", Richard Finch explains why the Corvair is such a solid engine design:

1. It has a very short piston stroke which greatly lightens the loads on the pistons, rods, crankshaft and bearings.

2. It is an opposed-cylinder design which practically eliminates loads on the crankshaft main bearings.

3. It is air-cooled which means it theoretically has the whole earth's atmosphere as a cooling supply. Its cooling system cannot deteriorate as can a car with water-cooling and the associated corrosion problems.

4. Its valve-geometry design is almost perfect for a non-overhead cam design and this results in a more efficient cylinder head. Efficiency in this case encourages mechanical longevity.

5. The valve rocker-arm design comes from the most-proved design in the world, the Chevrolet V-8. This ball & stud design came out in 1955 and remains basically unchanged today. It has been copied by many other manufacturers.

6. The toal engine design is simple and simplicity makes for longevity.

Those things are pre-requisites, no doubt. But there are other reasons the Corvair is a good auto-conversion for aircraft. One big reason is that there is a 50 year history of using them in aircraft. That history is important. Even if the spirit of the FAA rule allowing individuals to build experimental aircraft is to EXPERIMENT, meaning if you can demonstrate sufficient airworthiness to an FAA inspector you could fly with a Ford Model A engine, there just aren't as many flight hours on Ford Model A engines (at least documented) as there are on Corvair engines.

While that's important, there's an even more important thing to consider: Substantial testing has been done on Corvair motors as flight engines during the last 15 years by A&P mechanic William Wynn and many others. William in particular however pursues flight testing conversion ideas implemented on Corvairs -- then he PUBLISHES his findings on the Internet and in a Corvair conversion manual that he sells. William's willingness to share his knowledge either for free or for modest price (his manuals or DVDs or parts or services) is remarkable. His dedication to testing design ideas cannot be lauded enough. He may not be the only expert on Corvair engines, nor the only one who shares information, but I have not found any other person that has invested so much in the Corvair engine conversion and contributed so publically to the body of knowledge of what constitues the most reliable and safe Corvair conversion designs.

Visit http://www.flycorvair.com/ for more information on William Wynne's conversion work.

Since I am employed in an engineering field (software), I cannot overstate the importance of testing. An idea that looks very good or even like the best solution on paper may completely fail in practice. An idea that seems plain or less than ideal in theory may work superbly in the crucible of real everyday operation.

Auto engine conversions are by nature experimental, as the engine was not designed for flight. Therefore, any auto engine conversion is an experiment. That is why basing a conversion on the testing (not Internet opinion or assertion, but real in-flight testing) done by others can SUBSTANTIALLY reduce unknown factors and thus risk. Given a design that has been proven to work fairly well in flight, for many hundreds of hours, one can be more confident that following that design will lead to similar performance; on the flipside, even small deviations from a proven design can lead to in-flight failure.

All airplanes are gliders (recently demonstrated to the general public by C.B. Sullenberger and his first officer Jeffrey B. Skiles on US Airways flight 1549).

The gliders that are powered, like an Airbus 320 or single engine pistons like Cessnas or homebuilts, are the ones you don't want to have to glide with no power.

If you're looking to experiment that is fine -- know that your flights will be as a test pilot. There is nothing wrong with that. If you're looking for a reliable air-cooled conversion, the Corvair has a well-established, long, fairly well tested, and highly documented conversion history. Use it.

STOL Flight

When I first started thinking about flying I was motivated by the idea of getting from point A to point B without having to crawl along on a super highway at 50 - 60 MPH in heavy traffic when the posted speed limit was 70 or 75. I had long commutes between Austin and Fort Worth and after trying the "drive" in Microsoft Flight Simulator I realized that, with a fast enough plane, flying would turn a 3 hour high stress very boring drive into an hour or so of very cool adventure.

If I learned to be a pilot, I could kiss traffic jams, high speed jostles with hostile SUVs and menacing tractor trailers goodbye.

The more I played with the simulator, the more convinced I became, and one day I picked up the phone and called a flying club I'd tracked down in Austin with what seemed like acceptable training costs.

That day set me on the track of finding out I was completely wrong about using a plane to shave travel time off of what was a 3 hour commute between cities by car. It turned out I loved to fly, and I still would like to give some commuter flying a shot sometimes, but the reality and the flight simulator just ain't the same. No one, after all, just walks out to the parking lot where they work, jump in their Cessna, fire it up, and head off to the next city at 135 mph (faster, with a tailwind).

But during the process of finding out all the reasons why I had been mistaken, I learned that I really dug flying about 2000 to 3000 feet up, kinda slow, kinda low, gazing at the landscape and the life gliding by below me.

What kind of airplane would let me do that, and still get me places faster than a car on occasion?

Here's the answer: ZenithAir STOL Aircraft

That is a Short TakeOff and Landing plane that simply blows my mind. Here's some more links to videos on YouTube of these kinds of planes:

Canyon Surfing

CH750

There's a field near the building where I work; I used to walk out there and pace it out. About 800 feet long. Hmmm ... definitely could land on it, park the CH750 there in the morning and take off after work. Now all I have to do is figure out how to get the FAA to let me do it ...