A lot of you have e-mailed and asked what happened to my engine and why is it torn down right now. Incorrect air inlet baffling on the front of the cowl caused my two front cylinders to over heat. This in turn resulted in a cracked piston and a broken ring in the #5 cylinder. The resulting compression on this cylinder was 14/80. The opposing #6 cylinder had problems also with a compression of 25/80. The rings and piston on #6 were not broken or cracked but the rings were no longer sealed and the gaskets were leaking as were the gaskets on #5. The front cylinders were blocked from any direct cooling air as you can see in this link http://mywebpage.netscape.com/n886mj/baffles.html . Notice how the air inlet baffles cover the entire front of the cylinders. A costly design mistake on my part. The top half of the cylinders must be exposed to the inlet air. The strange thing is that my FSDO inspector did not catch the bad design nor did anyone else who looked over my plane. The photos on the link above were posted long before I made the first flight and not a single person on the net caught the design flaw either. That really surprised me since everything posted on the net is picked over with a fine tooth comb. Oh well, my loss, your gain since you learn from my mistake. I have a total of about $250 in repair parts (one piston, one full set of 6 piston rings, lifters, head gaskets, base gaskets, top engine gaskets, valve cover gaskets, push rod tube o-rings, push rod guide o-rings, etc.) headed my way and should be here by mid week. I have already surfaced my heads and cross hatch honed the cylinders and cleaned up the five good pistons. The re-build should be a piece of cake. If you guys remember, I had the EFS-2 crab which was too small and replaced it with a EFS-3. After installing the bigger crab, I did not get any performance increase and was doing everything possible to figure out why. I finally purchased a differential compression tester and that revealed the problem. Looking back over my flight records, I see where my oil temps went from 190° to 220° back on 4-7-05. I also made a notation that two days later, I had an oil temp spike of 260°. These temperatures were discussed in depth with very knowledgeable Corvair guys and I was assured by them that this was nothing to worry about. Of course I worried anyway and made several changes to my oil cooling duct to improve the temps. I honestly feel that the damage was done during the flight on 4-8-05 when the oil spiked to 260°. Since that day, I flew the engine for an additional 23.8 hours. Cruise ranged from 135 to 145 mph and climb out on take off was 1100fmp all the while basically flying on four cylinders. This is a testament of just how strong the Corvair engine is. I am extremely excited about getting back in the air with a healthy engine and seeing what increase in performance I get. Another point is that I only had one cht probe located at the GM stock location between #1 and #3 cylinders on the head. I highly recommend getting six probes for mounting under the spark plugs with a six way switch to monitor all six cylinders.
Mark Jones (N886MJ) Wales, WI USA E-mail me at flyk...@wi.rr.com Visit my KR-2S CorvAIRCRAFT web site at http://mywebpage.netscape.com/n886mj
