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Old 06-14-2022, 06:21 AM
RV6-KPTW RV6-KPTW is offline
 
Join Date: Oct 2014
Location: Sebastian Fl X26
Posts: 233
Default A couple of responses

Bsquared - the attached screen shot from my last flight looks like yours. I do not recollect seeing this EGT sag after warmup until this flight. EGT2 typically falls off for 30 seconds or so after start, no discernible impact to CHT. This flight, it occurred for the first time on climb-out. I think I have learned that once I start to see that initial EGT sag, it will not get better all by itself.

Merdad - the rope trick is threading a rope thru a sparkplug hole, filling the cylinder with rope, and rotating the prop to press the valve into the seat. I have done this once so far. Seems pretty easy. Getting the valve back in the guide valve the first time, on the other hand, is not easy. The first time took me about 2 hours and I think the 2nd time will take 1 minute.

Merdad - I have not talked to Jeff but did talk to lycoming support. This valve issue is somewhat common. I also attended the 1 week Lycoming engine school this spring, brought this issue with me for discussion, and heard war story after war story on this topic.

IR172 suggested that increasing CHT is not supported by the data. I tend to agree so will try to cool that cylinder a little more.

Kiwipete - I am interested in your ducting idea. Can you share pictures? One other thought I had was modifying the cowl ramp to divert more air to cylinder 2. I have already reduced the air dam to the minimum. Cylinder # 4 is cooler than # 2, and maybe I can change the ratio of air distribution a little. I have already addressed any baffle leaks on #2 / 4.

RocketBob mentioned using a ball hone hone rather than a reamer. I will consider this next time. This is a brand new engine and should not have significant guide wear. Also Oil life - I am changing from 40 hours to 25 hours on the change and will see how that works out.

Interesting how often this is occurring.
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Dennis Callaghan (X26)
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