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PA28 CHTs during climb

I will continued to work on the baffling and check ignition timing. There is almost no noticable difference in EGT between the two magnetos. I will let you know how it works out.

But tonight I need to fix a snag on the sistership…, so it will have to wait for a few days.

G

It is not unheard of that aircraft mechanics adjust the timing of both magnetos very precisely to … the wrong value. Better check your engine manual carefully. Some variants of the engines have other timing values as much as there are variants with different spark plug torque values. I’ve seen mechanics go for “standard” values without checking.

+1 on what Peter said on the top of the aft baffling. It do looks like the firewall is visible through the baffles, but hard to tell from the pictures.
Its also hard to see, but maybe some silicon could be used to seal the same baffles(metal parts) to the engine block.

When you had the top overhaul done, did they re-time the magnetos? If they did, then maybe it was mistakenly adjusted. Its easy to get it wrong after a long day at work….

spirit49
LOIH

You would have to be very stupid to adjust the ignition timing to the wrong value, the correct value is written on the engine data plate.

And yet I have seen it. If you do it several times a day, you can get sloppy and assume you know it by heart and don’t have to look at the data plate (which can be in a hard to reach place or difficult to read).

Depends on what kind of system you use to find the TDC.
Say you use the flower pot, and at the end of a long day you get a bit confused. And you don’t go far enough back on the impulse coupling.
Whatever can go wrong, will (eventually).
Just saying.

spirit49
LOIH

The last four pics are without the cowling, not sure where that comment went, it is not in the text…

Anyway, went to the airport(s) again yesterday and trimmed the baffling a few places for a better fit, which I hope will help. I will also seal off minor gaps with RTV sealant and report back to you guys.

Also went to the other airport, where the sistership is located. Sistership has an overhauled engine with 5 hrs on it. The baffles were renewed when the OH engine was installed. These were a better fit, sealed some gaps with hi-temp RTV, and repaired the stall warning (which was the main task for yesterday). I have ordered a CHT gauge for this aircraft as well.

TODO: Check CHR sensor calibration and magneto timing.

G

The essential point is that to get the seals to work well, one needs the stiffer ones (with the PTFE coating, slippery) on the top ones, and the floppy softer ones on the bottom.

Socata (and others) used the soft floppy silicone-cloth on both, and used springs to hold up the top ones, but after a few years this stops working.

You don’t need silicone to bridge the gap, and in any case the seal material will just flop back down anyway.

I posted photos of the seals I did here a while ago.

Administrator
Shoreham EGKA, United Kingdom

Some pictures of the sisterships baffles, which seems to fit very nicely with the cowling in place. This is the aircraft with the recently overhauled engine. The material is very basic rubber, it seems. We will see how it holds up.








Real nice baffles BUT at least 2 big HOLES :


FAA A&P/IA
LFPN
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