I write a lot about motivation and philosophy, and most of the stuff rarely generates email, but if I write a piece that sounds cranky, people write in response. Below, a few thoughts from builders. keeping in mind that independent, intelligent people often see things from a different angle, I rarely expect builders to see eye to eye on perspectives, and it worth including that I am often more entertained by people I disagree with than people who see a subject the same way. I am open-minded, notice that “Guy A” gets the last word on the subject with his own letter.I wrote a long detail piece on plugs a few months ago, to read it type the words “Spark Plug Woody Harris” in the search block on the above right.
At the very bottom is a very thoughtful letter from Harold Bickford on the article Mastery or ?. Well worth reading -ww
From builder Matt Lockwood:
Good points (pardon the pun). Speaking for myself, I have learned tremendously from you, WW, thanks for being a pioneer.
From 601 Builder/pilot and DVM Gary Ray:
“You are not alone.
I have seen similar behavior in my profession. If West Nile virus is reported in the press then all animals that die in the next year were one of the unlucky ones that got it. Or if the Chinese contaminate dog and cat food with sawdust, then all animals that die of kidney failure must have been poisoned even though no toxic agent has been found, no animal gets sick when deliberately fed the suspected food, millions of animals that have eaten it have perfectly normal health and blood work, and none of the tissue damage found on necropsy of animals that die is related to other cases. Or, when a client states that they think their cat is responding poorly to a vaccine that he got two months ago and it is making him sick, they are not convinced by me when I tell them that the tire imprint on the white-haired abdomen probably has more to do with his current problem. “
From west Coast Pietenpol builder Pete Kozachik:
“Hi William, I’m having a Dickens of a time with your tale of two spark plugs; seems I used the wrong gap on my test run some time ago. The last line in your piece calls for .016″, but I used the 1965 Corvair Shop Manual’s spec, .030″. I used AC-R44F plugs, and ran the test using high octane no-lead gas as prescribed. What gap should I have used under those conditions? Same as for 100LL? One thing I noted after the run was some wet(?) soot on one plug, which I figured was due to any number of things, but not the wrong gap. What’s your diagnosis? Best wishes, Pete”
Pete, I included your note here in case anyone else read the story and got a detail wrong: .016″ is a gap that is correct for a magneto ignition, as on the Franklin in part “B”. Corvair should have a gap of .035″ and use ACR44F plugs. Other ones work, but if anyone wants old reliable, this is the best set, especially if you are trying to track down any kind of issue of experimenting with some other variable. We soot on a plug on a first run is often assembly oil from the engine’s build up.-ww
From Builder Mr. Jaksno:
“Sorry to hear this. Aviation does not suffer fools. The rant was well deserved, AND instructional. Thank you for being a ‘Lifeguard’. And thanks for being the Godfather of Corv-air!”
If you read the letter from Guy A you will see he is a pretty good cat, just missed it on the plug issue. A lifeguard will rescue people, (I tried it once, worked, but I promised Grace that I would let professionals and those clad in asbestos extract trapped people next time.) Just think of me as a guy standing on the beach pointing out where the rip tide you can’t see is. -ww
From Builder Bruce Culver:
“Don’t that make your brown eyes blue…..?”
And a response from the ever mysterious “Guy A” Himself, with whom I had a very pleasant 25 minute phone call today. If I ever sound cranky in email, it’s probably an attempt at humor gone bad. There is little between friends that can’t be fixed with a phone call……Guy A is obviously a thoughtful guy who considers risk management seriously, he just missed a basic important point on his engine.
I (Guy “A”) had night of introspection, and not much sleep, after reading this over a few times. I know that I’m *not* a taker of unmitigated risks, as you might infer. Instead, like nearly all long-time pilots, I recognize that flying, especially flying an airplane I built-in the garage with an engine not originally designed for a plane, is an inherently risky activity. And I believe that the risk can be reasonably managed through precise construction and maintenance, well thought-out testing, careful operation, and learning from the experience (and mistakes) of others.
I retorque my wooden prop at every oil change, and I do those at short intervals recognizing that Rotella-T and a $6 oil filter are not expensive compared to the engine. I have two batteries and an alternator in my electrically dependent airplane, and every year at annual, I put in a fresh battery in the #1 spot and move the #1 battery to the #2 spot, so that I always have at least one battery that less than year old. The manufacturer says the batteries should last 6 years, but what’s a battery worth when you’re in the clouds, an hour from the closest airport, and the alternator belt breaks?
I change my tires before they’re bald. I use flight following whenever I can and file flight plans when I can’t. I check the weather before I fly, every time, and I talk to Flight Watch a lot when it doesn’t look good. I use carb heat at low power whenever it’s below 75 degrees, even if I know the relative humidity is 20%. I attend FAA safety meetings regularly, because that one minute reminder of something I’m supposed to know might make the difference, making the two-hour presentation worth the time.
When I had a certified plane, I only used the specified plugs, and I cleaned, gapped and rotated them on a regular basis. So how did it happen that I flat-out “missed” the *requirement* to use the right plug with the proper gap in my engine?
I could try to explain that the plugs I used *are* listed in the spark plug cross references, and that I ground tested a range of supposedly acceptable heat plugs, found no apparent differences and stuck with the middle of the range. I could note that I’ve flown probably 400 of the 500 hours on my plane with those plugs. I could mention that modern cars with computerized adaptive ignitions are much less sensitive to particular plug heat and gap, so it wasn’t on my mind.
But all that would just be underlining the remarkable strength and robustness of the Corvair design. During all those hours, I was probably getting less-than-optimal performance and building up lead deposits on the valves. And a choice to use conservative timing (about 28 degrees max advance), in case I had to run on auto fuel, probably kept me from seriously damaging the engine.
So I’m just going to say, “I missed it, and messed up.” My bad. Experimental aviation is supposed to be a long journey of learning, and now I’ve learned this one,Luckily, no metal got bent and no one got hurt. ACDelco R44F plugs, gapped .035-.040. Got it.
Final note – If you also cannot find these plugs in your local auto parts store, try Rock Auto on-line (www.rockauto.com) for the best price.
On the subject of Mastery or ? Builder Harold Bickford wrote:
It seems to me that when you build something from components or better yet from basic materials you have to learn about craftsmanship, patience, accuracy and so forth. By it’s very nature homebuilding is not instant gratification and that is a good thing in a society that seems to want things right now for little or no cost. It is better to invest yourself and learn than to simply have someone else say “this is the airplane you want”.
Certainly part of the building adventure has been to visit and work with a fellow Piet builder. He ultimately chose an O-200 which he rebuilt. The Corvair engine mount he had is now in my shop along with a Corvair engine on an engine stand that will be torn down when it gets colder Meanwhile the wood for the fuselage is ready for cutting and framing up while we still have nice temperate days. True it is labor intensive (and we are on a budget) but the point is that when done the Piet will be a known quantity and at virtually every point Edi and I will be able to say “we built that”.
“They were the best of plugs and they were the worst of plugs; It depended solely on which engine you screwed them in. Applications be damned, to hell with gaps! We’ll run what we like and blame the results on GM and William Wynne”
……The following story is true, the names have been changed to protect the guilty…………
Guy “A”, Sends several notes, calls etc. Reports his engine is running poorly after a number of hours. He is a technical kind of guy, interested in concepts like lean of peak operation, analysing performance, fuel additives, etc. We run through a pile of different possibilities. Thinking that it must be something that troglodyte ww did, he gets inside his distributor and starts changing stuff to see if he can cure an intermittent hard miss on climb out. It doesn’t do anything. (but mess up the distributor)
Along the way, It is discovered that one cylinder is blowing 50/80 on a compression test. This is now the new suspect for Guy “A.” He is sure of it. I carefully explain that a leaking exhaust valve will not produce an intermittent miss. I go in to explain that even if the engine had 40 over 80 on a differential compression test, this in no way is indicative that cylinder is producing 1/2 power. Even if a cylinder indicates this low, I seriously doubt that any more than 2% of the flammable air fuel charge escapes past the leak in operation. Just think about how short a period of time the compression stroke is on an engine turning 3,000 rpm.
After all kinds of communication and tests, some how we stumble over spark plug gaps and Guy “A” casually says he gapped the plugs correctly at .025″. I ask why on earth he would do this? Guy “A” feels that this is the correct gap for reasons he cannot explain. A moment later he reveals that he has NGK spark plugs in the engine! He thinks they are great plugs. I agree, pointing out that I always liked them in two-stroke dirt bikes, but that has nothing to do with Corvair engines in aircraft. I ask how he decided which NGK to use, he tells me he tried several, and it ran best’ on the one he picked out. (I wonder to myself how badly it detonated when he found the plug that was too hot.)
Guy “A” Complains that they don’t sell AC-R44F plugs in his local auto parts store. He goes on-line and finds out that the correct plug we tell people to use cost a whopping $1.44 a plug, far less than the incorrect ones he is using. He goes back and regaps his plugs while waiting for the correct ones, and Volia! intermittent miss gone (at least on the side of the ignition he didn’t mess with.) Today he sends me a picture of the incorrect plugs, he has 83 hours on them. The includes the opinion that they “look pretty good.” I point out that they are the worst looking plugs I have seen in a while. His return question is what is wrong with his motor that it makes the plugs dirty? HOW ABOUT THIS: ITS THE WRONG PLUG FOR THE ENGINE, AND IT HAD A GAP THAT WAS CORRECT FOR A LAWN MOWER.
Trick question: A guy tells you that he has been driving Corvairs for 25 years, he knows engines real well and he has had great results with NGK plugs in his Corvair. They are great to use right? WRONG. Don’t take advice from car guys. Show me the car guy who runs is car on 100LL all the time and cruises at 75 HP. A 1965-69 Corvair will break 100 mph on 75 applied HP. It is not valid data, it doesn’t apply. You can’t show me a land based corvair that only fills up at airports and always drives at 100 mph.
Here is my major problem, at Guy “A”‘s airport, a lot guys have watched his engine do this intermittent miss on many, many take offs while Guy “A” has been ‘testing.’ Do you think that each and every one of them will now be made to understand that the root of all of Guy “A”‘s issues is caused because he willfully ignored the correct plug for his engine, and then made up a new gap? No way, I am sure that the lesson that each of these people learned is “Car engines suck, Corvairs are bad, they are promoted by a fool, Since guy “A” has a PhD in engineering, if he couldn’t figure it out, no regular builder could.”
My second major problem is with anyone who has an issue with their engine, and the very first thing they decide is “It must be something William did or sold to me.” Statistically speaking, the last 50 times some one jumped to this conclusion, it was something they were doing 49 times. I don’t mind questions, but I do mind the assumption that I don’t know what I am doing, especially when it comes from a person who isn’t even willing to follow my spark plug recommendations. Think it over, Civility is a two-way street. Would you like me if I went to your place of work and always started communications with the assumption that suggestions you made are not worth following and the work you produce is the root of all my issues. How long are you going to be civil with me?
I like teaching people what we have painstakingly learned. Mistakes are ok, we can correct them, but let me point out that this entire wild goose chase was avoidable. It was caused by an attitude problem, a perspective that asking some people on the net and guessing was technically just as valid as all the reasearch, testing and operational data that I have gathered since 1989. -ww
PS: Lest anyone think I am just picking on Guy “A”, let me share a story of Guy “B”. Guy “B” is an old friend, and he owns a certified aircraft with a 150 hp Franklin, (Which has magneto ignition.) He is not an a&P , but does some Pilot preventive maintenance on it. When it is cool, it runs fine, but after a while, it runs poorly. Winter weather leads him to understand that he must have carb ice. This goes on for several flights, some of which almost end up as forced landings. Everything is considered the culprit, even the basic Franklin design. Steve Upson, old member of the ‘hangar gang’, and very stubborn mechanical detective makes it his personal mission to figure it out. After a long day, he asks the operator about the kind of work he did. He goes into how he cleaned the plugs and gapped them at .035″ Steve points out that this is more than two times the limit allowable. Owner chimes in that it works on all his cars. Steve asks how long he has had Bendix mags on all of his cars. Plug gaps corrected to .016″ plane flies perfectly.
EAA headquarters sent me a followup spread sheet with all of the data from last night’s webinar. It included about 120 questions that builders watching wrote in with. When we were doing the session, only the people at headquarters can see the questions, they didn’t come to my computer, so we relied on Charlie Becker picking out 20 questions that time allowed us to answer. Many of the questions were covered in the talk, but I wanted anyone who didn’t get an answer to send me the question directly, I will be glad to answer it for you. The EAA ia good about protecting the privacy of members, and the data we got was not tied to anyones email address, so it isn’t possible for me to answer the questions for people without them resending them directly.
One other note, several people mentioned that the program started 4 minutes late and had some audio difficulties. One or two comments suggested that we should have check the system earlier. Actually Charlie Becker is a stickler about doing just that. He gave us a long tutorial the day before, and insisted we run wire in the house and go out and buy the exact headset model he wanted. We did all these things. At 3pm, Charlie had us do a full dress rehearsal, including every element of the log in, it worked perfectly. We didn’t touch anything. We checked it 25 minutes before broadcast, and suddenly nothing worked in the audio. Grace and Charlie worked to reboot the system several times, and tried everything we could think of without avail. As we got to the last-minute, Charlie quickly hooked up a telephone connection through the EAA switchboard, and then through his office. Instead of everything going through the computer, all of the things I said in the entire interview went through the phone line, where we had little chance to control even rudimentary things like volume. Thanks to Charlie’s quick thinking, the show went on, with little noticeable issue. I asked Charlie if it had ever happened before, and he said that they had not had this issue ever. Hats off to Charlie for saving the day.-ww