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Happy New Year to all. It has been unseasonably fair weather here in western NY and thus the Taylorcraft and I have tried to capitalize. Last October I posted a thread regarding a stuck exhaust valve, and to be honest that sticks in my mind, constantly wondering if the engine is healthy, am I damaging it beyond the typical "parts are moving there is wear".
It was 39 degrees yesterday and no wind which means the Taylorcraft Gods were in agreement that I needed to leave work early and fly. Plus it would be the first time in the 3 years I've owned the plane I can say I flew it in January. Despite for the few days previous being in the low 20's, the poor man's heater had all external metal engine parts in the 60 to 75 degree range (per infared thermometer) and engine oil 62 degrees. It fired on first pull and ran smooth at 400 rpm. When I got back to the cockpit oil was 28 psi. I set the throttle to 900 rpm to warm it up. Density altitude was -400 msl, so takeoff performance fun for the C85-8. Tail up almost instantly and 1200 fpm climb to 2000' msl a little above best climb speed (130 lbs under gross).
The thoughts of that valve go through the mind again...... How would I know if I was chewing something up before it was too late? The engine feels normal, it's responsive to power changes, let's check some numbers and see if the data is helpful? I did speed runs in 180 degree tracks to average for wind at 2000 msl. At 2400 rpm (where my A&P told me to keep it, no less than 2300, don't baby it keep it warm), IAS was 108-110 mph and ground speed averaged 94 kts, at 2300 rpm IAS 102 mph and 88 kts ground speed. I had read about full power/max rpm and my A&P asked me to confirm it but not let go beyond redline, so balls to the wall and let stabilize at about 2560-2580 rpm (hard to be exact with old gauge), IAS was 118-120 mph and ground speed was 102 to 104 kts. I checked the ground speed and climb data against the cloudahoy telemetry and the numbers were consistent (very cool program). There was no detectable change in vibration perhaps a little smoother at higher rpm just louder. Keep in mind I don't have the wheel fairings on now, I do have the winter plate on and tape around it. Oil temp was in the 155 to 160 degree range which I thought low for a 40 degree day, but I have a lot air exit space on my cowl and no restriction to cylinders at front of cowl, new tight baffles.
Next after flying for 1.4 hrs and doing 4 landings (yes there were four approaches too, not bounces, LOL), it took 6.4 gallons of 100LL for average of 4.4 gph. Upon shot down I used the infared thermometer to get temps on the cylinders. My thinking if something was still stuck, I would have a significantly higher or lower temp on that cylinder. I shot the valve cover and the fin near the spark plug on each cylinder (always warmer there). All valve covers were in the 160 degree range with the back cylinders about 8 degrees warmer and on the fin was around 175 to 180 degrees with not much variation (4 or 5 degrees) from cylinder to cylinder.
It has been 12 hours of flying since they cleaned the carbon deposits out of the offending exhaust valve. After that fix the compression in all cylinders was 78 with one at 76. Unfortunately, I do not have the equipment to check the compression.
So my question to all of you with more experience than me and I don't know a ton about engines, is any of this indicative of an engine that's doing ok, or more importantly that valve is not sticking again? I realize it's hard to know what is going on inside an engine, but I've read articles saying a stuck valve you'll definitely know and others saying you may not until it's too late or you're at least doing a lot of damage. Maybe it's time to stop worrying about it and just fly it, but we love this little baby and want to take care of it.
I know this is a lot of stuff but hey, it's winter I know at least some of you will enjoy chewing on the data. :-) Thanks,
It was 39 degrees yesterday and no wind which means the Taylorcraft Gods were in agreement that I needed to leave work early and fly. Plus it would be the first time in the 3 years I've owned the plane I can say I flew it in January. Despite for the few days previous being in the low 20's, the poor man's heater had all external metal engine parts in the 60 to 75 degree range (per infared thermometer) and engine oil 62 degrees. It fired on first pull and ran smooth at 400 rpm. When I got back to the cockpit oil was 28 psi. I set the throttle to 900 rpm to warm it up. Density altitude was -400 msl, so takeoff performance fun for the C85-8. Tail up almost instantly and 1200 fpm climb to 2000' msl a little above best climb speed (130 lbs under gross).
The thoughts of that valve go through the mind again...... How would I know if I was chewing something up before it was too late? The engine feels normal, it's responsive to power changes, let's check some numbers and see if the data is helpful? I did speed runs in 180 degree tracks to average for wind at 2000 msl. At 2400 rpm (where my A&P told me to keep it, no less than 2300, don't baby it keep it warm), IAS was 108-110 mph and ground speed averaged 94 kts, at 2300 rpm IAS 102 mph and 88 kts ground speed. I had read about full power/max rpm and my A&P asked me to confirm it but not let go beyond redline, so balls to the wall and let stabilize at about 2560-2580 rpm (hard to be exact with old gauge), IAS was 118-120 mph and ground speed was 102 to 104 kts. I checked the ground speed and climb data against the cloudahoy telemetry and the numbers were consistent (very cool program). There was no detectable change in vibration perhaps a little smoother at higher rpm just louder. Keep in mind I don't have the wheel fairings on now, I do have the winter plate on and tape around it. Oil temp was in the 155 to 160 degree range which I thought low for a 40 degree day, but I have a lot air exit space on my cowl and no restriction to cylinders at front of cowl, new tight baffles.
Next after flying for 1.4 hrs and doing 4 landings (yes there were four approaches too, not bounces, LOL), it took 6.4 gallons of 100LL for average of 4.4 gph. Upon shot down I used the infared thermometer to get temps on the cylinders. My thinking if something was still stuck, I would have a significantly higher or lower temp on that cylinder. I shot the valve cover and the fin near the spark plug on each cylinder (always warmer there). All valve covers were in the 160 degree range with the back cylinders about 8 degrees warmer and on the fin was around 175 to 180 degrees with not much variation (4 or 5 degrees) from cylinder to cylinder.
It has been 12 hours of flying since they cleaned the carbon deposits out of the offending exhaust valve. After that fix the compression in all cylinders was 78 with one at 76. Unfortunately, I do not have the equipment to check the compression.
So my question to all of you with more experience than me and I don't know a ton about engines, is any of this indicative of an engine that's doing ok, or more importantly that valve is not sticking again? I realize it's hard to know what is going on inside an engine, but I've read articles saying a stuck valve you'll definitely know and others saying you may not until it's too late or you're at least doing a lot of damage. Maybe it's time to stop worrying about it and just fly it, but we love this little baby and want to take care of it.
I know this is a lot of stuff but hey, it's winter I know at least some of you will enjoy chewing on the data. :-) Thanks,
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