Builders:
In the last few days, A guy on the West Coast named Alan Laudani, who has questions about his running Corvair engine, went on the Corvaircraft Internet Discussion Group and wrote a story about his engine failing to turn enough RPM with a ground adjustable prop set at a very high pitch setting. He received a lot of speculative “advice” from people who have never seen the engine in question, and in all likelihood have never met Alan.
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They offered the following “Ideas”
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Ed Lee said the cam timing might be wrong and said he was certain it should turn more rpm because his much smaller wood prop does……..
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Mark Langford gave an example of a person with the wrong cam in his engine, referenced a computer predicted result, and suggested the engine be tested with a known prop previously run on the same size Corvair. He went on to suggest running the engine without a prop to check the timing, because it was ‘less risk to life and limb’…….
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Roy Szarafinski said several things, but suggested checking the compression, he went on to suggest the mixture could be very wrong on the motor……….
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Earnest Christley chimed in to suggest a compression check, asked if there was a lot of blow by, and went on to speculate that it had the wrong head torque, and Alan should seriously look at the possibility that the engine has broken piston rings………..
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Somewhere in there Dan Weseman, pointed out that the engine had been run already at a Corvair College, ……but this comment was ignored by the speculators who had never seen the engine, but were sure they knew it had something wrong. Notice how quickly they escalate to ‘broken piston rings’.
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Above, a picture I took myself, May 9th 2016 in Cloverdale California, where the engine in question had just been run on my test stand. Unlike the people on the discussion group, I had seen the engine run in person, and had worked directly with Alan. I even documented it on my website. The picture is Alan standing beside his engine just before the run. Read the story: Alan Laudani 3,000 cc runs at CC #38, and in case you think it is a hoax, read the Comments also, where Alan includes his email address and thanks several people, including myself and Jerry Price for working on the engine. I’m kind of wondering why Alan went to the internet to find strangers to comment on his engine instead of contacting myself or Dan, and I’m really wondering why he failed to mention to anyone on the net that I had driven all the way from Florida on a 7,200 mile circumnavigation of the US, and Alan’s engine, and all the others on the trip, were run at for free at the events. Evidently he values the speculation on the net over direct in person assistance.
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In case you are wondering:
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I ran the engine myself and it was in fine working order.
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The cam timing was not wrong, I can spot this in an instant by watching the motion of the #1 intake rocker and looking at the timing mark on the balancer.
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The warp drive prop on Alan’s plane can not be compared to the wood props mentioned. The diameter of the Warp prop will not allow it to turn the rpm of a 54″ wood prop.
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The engine was run with the prop pictured, my test prop, which has run more than 300 Corvair engines in the last 14 years. ( It has been repainted, but it just ran 4 more engines last weekend) I always have an optical tach, my $79 Equis timing light has a built in digital tach, and after 300 engines on the same prop, I can usually call the rpm of a Corvair plus or minus 35 rpm by sound and throttle position alone. ( If you want to lose $100, bet me I can’t do this at the next Corvair College). I have said this countless times, no Corvair should be run without a prop. There is no cooling, but more critically, the prop is the ‘governor’ which prevents the motor from hitting 7,000 rpm in the blink of an eye.
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I can also tell the compression of a Corvair by turning the prop over by hand. In setting an engine up on my stand, I always do this, and after hundreds of them, it is easy to tell by turning the prop if each individual cylinder has compression. Also the suggestion the motor might be running with the wrong mixture comes from the very person, who along with Ron Lendon, caused this mess: Safety Alert: Excessively Rich MA3-SPA Jetting..
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All engines run on my stand are observed for blow by out the vent tube, 15 years ago I did extensive volume measurements by timing the flow to inflate a 30 gallon trash bag. I an say that Alan’s motor had completely normal blow by for an engine breaking in. There is no way, short of heads so loose it didn’t squeeze the gaskets, that low rpm could be caused by head torque. Know this: an engine with a blown head gasket will make more than 90% of the rated static rpm. Leak down has very little effect on static rpm. ……and let me add that it 29 years of doing this, I have had an occasional builder break a ring putting the piston in a bore, but never, not once, have I ever had a builder break any piston ring on the test run, not once in hundreds of runs.
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OK, so what is wrong with Alan’s motor?
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Simple, he is using a junk tach, that he says in his post will not even read above 2,000 rpm, additionally he mentions trying to run it directly of his MGL “glass cockpit” although I have very specifically warned people to NEVER do this: MGL vs Corvair ignition issue. In short, Alan has no idea what rpm his engine is turning. He could just use a cheap timing light to get real numbers, but he would rather short out his ignition by wiring it to a South African “Glass Cockpit” maybe time to pay attention to basics and buy a timing light. Spending thousands of dollars on an imported screen that has a notorious ability to hurt ignitions, and then trying to run a junk Westach tachometer is an example of poor decision making.
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On the internet Alan now states with the tips at 6 degrees, ( a setting way too low to fly ), it only turns 2,710 rpm. A Standard 2,700cc Corvair can turn the same prop that rpm with 2.5 more degrees of pitch. The only reasons why Alan’s 3,000cc Corvair would yield that number are 1) the tach is wrong 2) He isn’t measuring the pitch correctly, 3) If he actually did try to extensively run the engine with 15 degrees of pitch, and held it at wide open throttle with the rpm below 2,200, he very well could have damaged the engine by detonating it. There is a reason why I tell people the 2,700rpm should be the minimum static rpm used. read:Critical Understanding #2, Absolute Minimum Static RPM., which includes the quote “The primary group violating this Critical Understanding of Corvairs are builders who have made their own props and builders using a ground adjustable props with too much pitch in the setting.“
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Alan started out with a ridiculously high pitch setting, and now is trying a ridiculously low one. I would have told him this if he bothered to call.
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Hey William, if you have all the answers, why don’t you go on Corvaircraft and set Alan straight?
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