912UL pneumatic sync on condition?

by Adam Messer in 912 / 914 Technical Questions 5 years ago

It's been about a year and about 80 hours since my last pneumatic sync. In level, coordinated flight the EGTs remain within 10°F of each other. Knowing that EGT mismatch indicates a carb sync issue, can I delay the pneumatic sync without sacrificing performance?

Re: 912UL pneumatic sync on condition?

by Mike Willey » 5 years ago

Mike Willey

1 1 1

Time between carb sync is somewhat dependent on the stability of your throttle linkage and cable installation. Mine is stable for much longer than 80 hours although I usually check it at Condition Inspection time. Throttle sync is much less of an issue at higher throttle settings and so not sure if EGT is a good measure. The only real way to check is to test and see how stable yours is over a longer period of time ( at idle and about 2500 rpm, where it will show up the most) and then use that as a guide. You did not say how you are doing this, but using the digital carb synch tool makes it much easier.

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Re: 912UL pneumatic sync on condition?

by James Ott » 5 years ago

James Ott

22 321 357

My carb sync stays stable for about 300 hours, but I put the gauges on and check it every 100 hours.

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Re: 912UL pneumatic sync on condition?

by Adam Messer » 5 years ago

Adam Messer

20 29 59

I conducted a mechanical and pneumatic sync using dual analog gauges. Previously I verified that the gauges reported the same vacuum pressure by connecting them to a vacuum sealer through a T-connector.

There was a significant vacuum pressure difference at both low (idle) and high (3500) rpm. Following the sync the EGT mismatch is the same or slightly greater than it was prior to the sync. But the engine runs MUCH more smoothly over the entire RPM range. How did I miss this?

My conclusion is that for sure a big EGT mismatch indicates carb sync issues, but that mikewings is completely correct in stating that just a close EGT match does NOT mean carbs are synched.

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912UL pneumatic sync on condition?

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