There are countless techniques and lessons we teach by example and hands on training at the Colleges. Here I would like to focus on four tasks that every builder should know as part of having complete mastery of his or her engine. These four skills are 1) Installing and timing a distributor, 2) Running and correctly interpreting a differential compression test and 3) Correctly setting the hydraulic valve lifters. 4) pre-oiling the engine.
At the college I will teach these tasks to many groups of builders 5 or 6 people to a group. Part of my learning process it to immediately have builders repeat the process they just observed so I can answer their questions and closely watch how they do to make sure they understand and have possession of the skill. The tasks are not difficult, but the are different. 85% of our builders are from outside the mechanical world. This is an important distinction. My useful definition of working in the mechanical world is simple; Do you pick up hand tools at work nearly every day on the job? The vast majority of homebuilders do not, and I adjust the learning process to accommodate this reality and give many more builders a much better understanding of their power plant.
I am a middle-aged, long-haired opinionated troglodyte from rural Florida. If I had to earn a living at any task that involved appearance, political correctness or tolerance of intolerable people, I would live in poverty. If I was also required to have IT skills at these tasks, I would starve. My hat is off to our builders who can thrive at such tasks, you are better men than I. This said, my record says that on the subject of being able to teach people how to master simple aircraft engines, even people from outside the mechanical world, I am pretty darn good.
There are a number of factors on why I am good at this. I like people, and I like learning myself. I spent 11 years of my life in college, 8 years full-time and 3 in night school. (This is really ironic because I was expelled from high school on the grounds of poor attendance) I know and love the subject at hand well, and I have honed the transfer of information over 20 years. All of us had teachers who gave the same lecture if there was 50 people 5 people or 2 sacks of potatoes for students. I learned from many very good instructors, and the best always tailor the delivery to the student. After many years I am a keen observer of people learning, and I watch small signals like body language to instantly recalibrate the delivery until message sent=message understood. I may not always look like it, but I am paying detailed attention to builders at colleges. A big College may have 75 builders, and in the 3 days we are there, I am going to adjust the process and delivery to tailor it to each of these 75 individuals.
A guy who works with tools every day on the job and is constantly exposed to having to master a physical skill or understand how a mechanical sub system works often picks up something like distributor installation on a simple presentation and observation. People who work at desk jobs or cover non-mechanical subjects for a living gain a lot from directly repeating the task step by step right after observing it. The flexible lay out of the college allows both of these builders to learn at their own pace, at the same time. The primary thing I am watching is that the builder is comprehending and performing the task correctly. Good delivery is important, and the setting is casual, but I don’t just assume that people got it. I ask people to perform the task, and then I will often ask them to show it and explain it themselves to another builder. This is the best confirmation that they have real possession of the skill.
I am writing up notes for the four tasks, something of a checklist for people to have on hand at the college. I will expand on these here after we return. For now, some source notes:
1) Install and time a distributor. This is already documented very well in print and pictures, but I do go over it many times in person. I do not allow a builder with a complete engine to leave the College without being able to demonstrate to me that he can use a timing light, and that he owns one. If he doesn’t have one, we sell him one on the spot. Your flight instructor didn’t let you solo a plane without certain skills like being able to land. I am your engine instructor, and before you go home solo with your engine you are going to understand ignition timing and how to use a timing light. The distributor instructions ar on the products page of our website and they come with every distributor we sell. look at this link http://flycorvair.com/distributor.html
2) Run and correctly interpret a Differential compression test. Just yesterday I got a letter from a builder referencing a compression test saying that he had compressions “between 165 and 180 psi” These are automotive numbers not differential compression numbers. Aircraft numbers look like 78/80 or 76/80 etc. I can’t say it enough times, but an auto compression test is like a stethoscope, and a differential compression test is like an MRI and a CAT scan. Which do you think are more powerful tools? Every annual on a certified aircraft requires a differential compression test. The tool is about $70. The most important thing I know about a guy who has a running engine but still sends me automotive numbers is that he isn’t learning anything: he is resisting treating the engine as an aircraft engine; he wants to ‘show me’ how he and his local buddies have always done it. This type of resistance to learning new processes usually just means the guy is stubborn. In aviation, this type of attitude isn’t just tiresome, its dangerous. Being willing to learn how to use a differential compression tester sets you apart from people with shade tree mindsets.
3) Set the hydraulic valve lifters. This is descriptively covered in the manual and it is visually covered on engine building DVD#3, But it is best covered in person. Increasingly people work at jobs that require little manual fidelity and feel. Right now I am typing this on a keyboard that will produce the exact same character if I lightly tough the key or I hammer down on it. We drive cars that are dumbed down with things like ABS and handling characteristics to protect the poorest or most impaired of operators. thankfully, flying is still very far away from this. So is building things with your hands, where feel counts. Setting the valves is an easy skill but if someone is coming from the ‘touch doesn’t matter’ world, they have to slow down a little and get the feel of what is going on. There are 12 of them per motor, and you can set each one several times to get the feel of this, it isn’t a task that you do just once per motor, nor a skill that has to be done in a short time window. Once set, they are good for the life of the engine and never need to be readjusted.
4) Pre-oiling the engine. This is a fairly simple process, and we have a very good set up for this on the test stand. At the college I will get someone to make a 3 minute You tube video of the basic elements of this and post a link to it here after the college. It is something important that requires no tools of value but it does start the life of your engine on the best possible footing. We pre oiled the panther engine for more than an hour. During this time, the oil in the engine went through the filter more than 300 times before the engine ever started. The Corvair is one of the very few engines for light aircraft that can have this done. You can’t do it on a Lycoming without a very elaborate set up, and I have never hear of people being able to do it on other engines. “Buy it in a box’ engine people don’t care about details like this because people shopping for an appliance don’t think like this. However, thinking like this is at the core of being a motor head, a term that I am very proud to be called. It is not a title you can buy, it something you know about yourself after you actually learn and posses skills to take care of yourself mechanically and after you have chosen not to be a blind appliance operator, but a skilled aviator.-ww
About William Wynne I have been continuously building, testing and flying Corvair engines since 1989. Information, parts and components that we developed and tested are now flying on several hundred Corvair powered aircraft. I earned a Bachelor of Science in Professional Aeronautics and an A&P license from Embry-Riddle Aeronautical University, and have a proven 20 year track record of effectively teaching homebuilders how to create and fly their own Corvair powered planes. Much of this is chronicled at www.FlyCorvair.com and in more than 50 magazine articles.