Phil Maxson goes to 3,000 cc for his 601XL


Well known Corvair/601XL builder and pilot Phil Maxson of NJ came to our place this last weekend to reconfigure his 2700c/GM 8409 crank engine to 3,000cc/Weseman Billet crank configuration. Phil has made a great number of contributions to the Corvair movement, and Grace and I were happy to provide the tools and assistance to help him reassemble the engine and test it in 1.5 days of work, and still drive. 1,000 miles home on Monday to be at work this morning. He flies out of Sky Manor airport in Western NJ, and after he reinstalls the engine and has a short test period, his next long cross country will be to fly to Corvair College #31 in Barnwell SC in November.


Phil has been flying his plane since 2006. Since then he has flown it to numerous airshows and colleges up and down the East Coast.  He is currently working on his next aircraft, a Panther, also to be Corvair powered.


Moving to 3,000 cc and changing the crank required a bit of advance planning to get everything to come together in one weekend. The Weseman billet crank, (#1001B), requires advance ordering, and Phil also elected to use a set of Billet Rods from the Wesemans. Phil mailed his case and heads down in advance and we machined them to accept one of our 3,000cc kits, (#3000cc). Phil did his homework with our checklist and made sure he had every nut bolt and gasket, and the assembly went smoothly.


After we closed the Case, Dan Weseman stopped by to supervise the Gen 2 bearing installation, and Phil went the rest of the way through the assembly process himself. In his youth he wrenched on motorcycles for a living, but he has long worked in the world of corporate management. I have pointed out many times that our system is directly geared to teaching builders how to do things themselves and does not require previous experience in engine building. Phil is a good example that success is based on following our information and instructions, and not previous experience.


Last year at Corvair College #27 in Barnwell we awarded Phil The Cherry Grove Trophy ( read: The Cherry Grove Trophy.) for his contributions to Corvair powered flight. The most outstanding of these is his creation and management of our Zenith information board, an on line discussion group where builders of the Corvair/Zenith Combination exchange detailed factual information on operation data in those airframes. To learn about our Zenvair discussion group click on this:‘Zenvair’ Information board formed and:‘Zenvair’ information board, part #2.


Phil authored a motivational perspective for us that is well worth reading by any Corvair builder, you can find it at this link: Guest writer: Phil Maxson, flying a 3100cc Corvair in his 601XL . If you would like to see a YouTube film of Phil’s plane flying over Florida Atlantic coast, check this out: . Because Phil is from West Virginia, his friends refer to the film as “the yee-haw heard around the world.” When I introduce Phil, I call him “The second best pilot from West Virginia.” (Chuck Yeager’s home state is WV) Phil is a good sport and goes along with all this with a smile.



Phil during the first five minutes of the run, in our front yard by the side of the runway. The stand is chained down to a 700 pound concrete block cast in the ground. Look over Phil’s shoulder and you can see Dan Weseman landing the Panther on the centerline of the runway. When we started Phil’s new engine, the sky was already filled with the sound of Corvair power, as Dan was doing aerobatics overhead.



 Phil and Grace check out the engine from all angles. It was a smooth run, and it didn’t leak a drop of oil. Pressed for time, little effort beyond a very good cleaning went into esthetics. Not the valve covers still say “100hp” instead of “120hp”. Just behind the engine is the red strobe light that I have fixed on the run stand. It eliminates fumbling with a timing light in the prop blast and allows one person to work the throttle and set the timing himself. Summer will still be here for a while in Florida, it was 90F outside. Most of the engine assembly was done in my workshop which is heated and cooled. After it was put together the engine was put on the test stand in the main hangar which is a plain metal building that is ambient temperature.


After a first run, we brought the engine back inside for a few adjustments. Phil’s started needed a tiny ring gear clearance adjustment that took 5 minutes. The second item took about an hour. One of the primary items I want to see on a test run is the “Hot idling oil pressure.” We do not run oil coolers on test runs because I want to drive the oil temp above 260F (trust me a brand new engine is far better off being lubricated by 260F oil than 160F oil) for several reasons like cleaning out assembly lubricants and making sure that the oil is very thin and get to every spot in the engine. Oils protect metal parts simply by getting in between them and being there to allow an action akin to hydroplaning. Oil does not need to be cold nor thick to protect an engine, what is simply needs is to actually be “there”, at the potential point of contact, and it gets to these places on a new motor by being hot and thin, not cold and thick.


After the oil and the engine are very warm, I pull the throttle back to low idle and look at the pressure. Phil’s engine had a high volume clarks pump on it since he installed his Weseman bearing at Corvair College #17.  (This predates the existence of our CNC high volume pump) Under our test, the oil pressure was down near 5 pounds. The engine will not seize like this, as an idling engine will get by on very low oil pressure, but it isn’t a condition to tolerate. What was driving this is the basic desin of the clarks pump, which has a multi piece cast housing held in alignment with hand drilled 1/16″ roll pins. This requires far more tip clearance on the gears not to jam, and when the oil is very hot and thin, it allows the pressure to drop off at idle ( it still works at cruise rpm)


I didn’t change Phil’s oil housing to one of our #2000HV units on assembly, because I have seen some clarks pumps pass the hot idle oil test, and I didn’t want to spend Phil’s budget if it was not required. The variation in manufacturing produces the random success, whereas our one piece CNC high volume oil pumps always work because they are aligned on the extended shafts and not the roll pins.  We brought Phil’s engine back in the hangar and changed just the housing over the gears and the idler shaft. This didn’t even require pulling the engine off the run stand. We took it right back outside and ran it up again to full oil temp, and this time the hot idling oil pressure was 23 psi, a very large improvement. When the throttle was advanced even slightly, the oil pressure when right to the regulated limit pressure. This is how a high volume pump is supposed to work. If you would like to read more about the design of the part, look at this link: High Volume Oil Pump.


Above, Phil Maxson with his Corvair powered 601 XL at Corvair College #24 in Barnwell SC. Although it was a number of years ago, I can remember the clear co0l skies and the day with builders and friends just as if it was yesterday. -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 and in more than 50 magazine articles.

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