Breaking in a Freshly Overhauled Continental o-470R

We are at 25hours since all the cylinders were replaced on our 0-470-R (so just a top end break in). The 25hour mark also aligned with our annual. The strainer looked great according to the mechanic. All compressions were good with the lowest being 74/80.

We pretty much did what everyone has mentioned above, flow low and fast at 75% power. We added 1qt at the 14th hour. By the 25th hour I would guess we were down another 2/3qt before doing the full annual oil change.

One thing I didn't see mentioned above - we were basically advised to "cross country" it or more specifically, to try and fly it for at least 1hr at a time. No short/quick flights. So, we had fun and got places fast! And she guzzled a lot of gas, not uncommon to be burning 14+ gal/hr.
 
JoseCuervo said:
I always lean for taxi, then lean for take-off. Assume "leaned for best power" is same as leaning as required, rich of peak?
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As DT posted about five years ago:

Dan Thomas said:
EGTGraph.jpg
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Of course...you do have an O470...and, as such, you'll be lucky to get two cylinders running at best power at the same time considering how FUBAR'ed the intake system is! :)
 
timwinters said:
As DT posted about five years ago:



Of course...you do have an O470...and, as such, you'll be lucky to get two cylinders running at best power at the same time considering how FUBAR'ed the intake system is! :)
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What does that graph tell me???

In English, por favor???
 
Sinistar said:
We are at 25hours since all the cylinders were replaced on our 0-470-R (so just a top end break in). The 25hour mark also aligned with our annual. The strainer looked great according to the mechanic. All compressions were good with the lowest being 74/80.

We pretty much did what everyone has mentioned above, flow low and fast at 75% power. We added 1qt at the 14th hour. By the 25th hour I would guess we were down another 2/3qt before doing the full annual oil change.

One thing I didn't see mentioned above - we were basically advised to "cross country" it or more specifically, to try and fly it for at least 1hr at a time. No short/quick flights. So, we had fun and got places fast! And she guzzled a lot of gas, not uncommon to be burning 14+ gal/hr.
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I don't ever go do pattern work (rarely) or just go up for a short ride. So, 2-3 hour legs will not be a big change. The full power stuff might be a bit of change, as I do sometimes throttle back.
 
Mogas.....run it, just keep it extra rich to increase detonation margins.

Mineral oil. Dump it at 3 hours and at another 5 hours then change the filter and refill with your conventional oil and change at 15 hours and your done.

The concern is when the piston ring to cylinders fit isn't broken in the hot, abrasive blow by gasses are in excess and we already know that there is not a extra margin of safety when it comes to lifter and camshaft wear.

It also is possible the rings can set in the first climb out, so if after a few hours oil consumption has stabilized drain the oil and refill with conventional.

Most importantly, run it hard but do not, DO NOT get it hot. Chts less than. 380 during break in preferably 350. If it requires running full cowl flaps, then so be it. We want to set the rings not warp them. The temps between the rings and cylinder will be way higher than normal as the rings are shearing down the peaks and valleys in the fresh hone job of the new/rebuilt cylinders. 23" or 30" of MP, or any where in between just run it rich and hard but do not, do not absolutely do not get it hot.




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Aaronk25 said:
Most importantly, run it hard but do not, DO NOT get it hot. Chts less than. 380 during break in preferably 350. If it requires running full cowl flaps, then so be it. We want to set the rings not warp them. The temps between the rings and cylinder will be way higher than normal as the rings are shearing down the peaks and valleys in the fresh hone job of the new/rebuilt cylinders. 23" or 30" of MP, or any where in between just run it rich and hard but do not, do not absolutely do not get it hot.
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While I'd agree <380 is an ideal state, don't fret above temps over 400 on a parallel valve 540. Over 450 is where I'd start getting concerned (redline is 500). On the Aztec (which had terrible cooling, admittedly) the CHTs got around 440 to start, and quickly dropped over the course of the first few hours. You can literally watch the cylinders break in on your engine monitor. I put another 800 hours or so on that engine, and I don't think any compression number got below 75 in that time.

And if you don't have an engine monitor, I wouldn't pay much attention to the factory single-probe CHT. Those, well, are pretty worthless.
 
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