Ross, I have no idea how long it has been since you held a Corvair head in your hands, or how many you worked with, but coincidental to the discussion, I spent all weekend prepping 16 pairs of heavy cast 66-67 110 heads for processing, starting with removing the seats and guides, milling off the carb flanges, and cleaning them. I have about 100 heads in my hangar right now. I don't have to rely on memory, I work in the hangar 10 feet from my house every day. In your writing you make reference to you having built all types of engines, and knowing them in some detail. Conversely, I have spent the last decade or two working almost exclusively on just one engine, in the single application of flight. Yes, I know that comparing the weight of heads isn't directly comparing their cooling potential, I was just making a rough point since they are both aluminum, and designed as air cooled heads, the comparison was good enough for the point, and a lot easier than figuring out the exact square inches of cooling area. Over the years I have learned a lot about much more important points, like how much detonation suppression you can get out of enrichment on takeoff with specific compression ratios, fuels, quench areas and ignition timing at various OAT's. I have seen countless heads with imbedded gaskets, and I can share why some engines can sustain 500F cht without damage, but another indents the gaskets on the take off with the cht indication below this. I know this one motor pretty well. None of the stuff I share is intended to be confrontational or caustic, or even really an element of debate. Just trying to share some of the experience from working on different levels of this stuff personally for a long time. I shared the Lancair IVP pictures to say that I once worked on that end of aviation, but personally chose to use my time since then in pursuit of making learning and personal flight more accessible to people who represent the majority of the rank and file EAA members. Looking back at the photos, I can say a lot of spectators were impressed when we brought the Lancair to Oshkosh, but this doesn't compare to how I feel when we are packing up from a Corvair College where 15 or 20 new engines ran, built by the people who will fly them. Ross, I don't know if you remember this, but I contacted you by email last year and offered to send a free copy of our 250 page new manual, as a courtesy, so your comments might better reflect what we are doing today. I never heard back. When you make a comment about my website saying I have never seen a cracked crank, perhaps you are looking at some dated material? Just typing "Cracked Crank" in the search box on the bottom of the front page produces this: Crankshafts 101 at www.FlyCorvair.com, a story about how we tore down a number of flying engines and tested all their cranks, and found some cracked. It is long, factual, frank and detailed........and it has been there every day for 10 years In a previous post you said something about there being people who "knew a lot more about Corvairs" than I do. Having never met me, and not having read my book, I am not sure how you evaluated that, and If we were speaking of just flying Corvairs, I could disagree with you. You mention people, but not by name, don't say which shops are you are referencing. I don't really care, but for my own notes, I like to share names and photos when making statements like that. But lets just say you are right, there is some guy out there who has a gods eye view, knows everything and has an IQ twice mine, and he is even a nice person. OK, he wins the smartest Corvair guy award.....and this does what for the homebuilder who wanted to learn something, build and fly his own plane? If that guy doesn't share what he knows, have a name, website, teach seminars for free, test stuff and share the results, answer questions and make some parts, then what he knows is only good for winning the title of "smartest Corvair guy", and I am not seeing that by itself as the basis of a useful life. I only contend that I happen to be the most experienced accessible guy on Corvairs, and my work has brought a lot to grass roots homebuilders.-ww. -------------------------------------------------------------- Here are the actual CHT numbers we have observed on fly planes and the limits I recommend: Corvair CHT, letters and notes. | flycorvair For people who like data in formalized spreadsheets, a 6 cht / 6 egt 601XL CHT info taken from test flight of 601XL | flycorvair A comparison of why the spark plug is a poor spot to take CHT Measuring Cylinder Head Temps on Corvairs. | flycorvair More info to read, integrating inlet size with discussion CHT part #3, Letters, notes, sources and inlets. | flycorvair Another part of the same article CHT Part #4 more notes | flycorvair Spread sheet data taken from a 2850cc Zenith 750 CHT part #5, flight data from Zenith 750 | flycorvair A Pegziar, 601XL and 701 from our hangar: Corvair Cooling, Three 2007 examples from our hangar. | flycorvair Something informative and slightly ironic Cowling Inlet Area, marketing, accident stats, Darwin where are you? | flycorvair An in depth study of a series of mistakes made on an eyebrow cooling arrangement on a Pietenpol Pietenpol Engine Issue Thank you, -ww.