Brian, I just took a close look at the head. There is no soot in the intake log that I can noticeably detect. My heads were done by a very close friend who is a perfectionist when it comes to detail and is also a builder of experimental aircraft and engines. The seats in the head are original factory (as far as I know) as they were not replaced when the heads were rebuilt. They were ground and lapped. If you remember, last year, I had to replace the # 5 and # 6 pistons and rings due to overheating because of a cooling issue . http://www.flykr2s.com/enginebaffles.html The number 5 was damaged the most. It is suspected that this damage loosened up the seat which caused it to slowly work it's way out. The reason I say slowly is because back at the first of this summer, I began to notice engine roughness which kept getting worse at the summer went on. All the time I was looking at carb and airbox issues. I had done a compression test shortly before the roughness began so I never thought that compression would be an issue. After I repaired the carb and still had a rough running engine, that is when I did another compression test last weekend.
Mark Jones (N886MJ) Wales, WI Visit my web site: www.flykr2s.com E-mail: [email protected] ----- Original Message ----- From: "Brian Kraut" <[email protected]> To: "KRnet" <[email protected]> Sent: Monday, October 23, 2006 6:58 PM Subject: RE: KR> Engine compression loss > With the intake valve open when the plug fires would it ignite the fuel in > the cylinder and intake? I would imagine that would cause the other two > cylinders to draw in a bunch of exhaust and cause all kinds of power loss. > Might even travel back through the intake and cause problems on the other > side of the engine. > > Mark, is there any soot or other evidence in the intake manifold > indicating > fuel burning in there? > > Who did the heads on your engine? Were the seats replaced, just ground > and > lapped? > > Brian Kraut > Engineering Alternatives, Inc. > www.engalt.com > > -----Original Message----- > From: [email protected] [mailto:[email protected]]On > Behalf Of Colin Rainey > Sent: Monday, October 23, 2006 3:09 PM > To: KRnet > Subject: KR> Engine compression loss > > > Mark and netters > Losing the #5 intake valve would cause the air fuel mix that entered the > cylinder to be expelled back into the intake head area, causing the next > intake of either #1 or #3 to be very complete as it would temporarily act > similar to a form of boost, making pressure in the intake. At lower rpms > it > might possible cause the next cylinder to have a lower charge due to the > reversion of the flow, but the third in the series would be unaffected. At > higher rpms, this would be negligeable. Since #5 was making no > compression, > the engine would have to lug the mass of piston around as well as making > power to run, so it would affect power by more the 1/5, more like 30 to > 40%. > You would also feel a very pronounced missing due to the dramatic > difference > between a cylinder that makes decent power and then the dead one. > > My opinion about the progression of your problem is that you began to run > rich due to the carb issues, the associated carbon buildups resulted in > hot > spots in the cylinders, which lead to pre-ignition and detonation, which > damaged the head area immediately around the intake valve. The carbon > buildup would act like little matches lighting off the fuel early, > especially when you ran the auto pump gas. > > JMHO... > > Colin Rainey > Independent Loan Officer > Branch 2375 > Apex Mortgage Company > 386.615.3388 Home Office > 407.739.0834 Cell > 407.557.3260 Fax > [email protected] > > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to [email protected] > please see other KRnet info at http://www.krnet.org/info.html > > > > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to [email protected] > please see other KRnet info at http://www.krnet.org/info.html
