OPs update on first flight, this got a little long...
Well I took her up today for three flights totaling a little under 2 hrs flight time. To recap, this is a first flight with this new IO-375 engine but the airframe has about 400 hrs of Subaru time on it, RV7A. So firewall forward is all new in addition to a major rewiring job, new panel etc. Running dual Pmags and EICommander. For initial flights I modified one of the extra timing curves for a max advance of 26 degrees, pretty much making them into good magnetos
.. In flight I was seeing 28 degrees advance for some reason but this did not seem to cause any problems at all.
On first attempt to start I flooded it bad and learned that the old PC680 is not up to the task of turning the engine over with the spark plugs in
I put in my back up battery and it seems to be in better shape, at least I got it started. I will have to get a fresh battery coming. Both of the batteries I had laying around have seen lots of duty on the Sube installs.
I did an offset departure as planned, climbing right up into the down wind to make it much easier to get back to the runway if needed, wasn't needed.
The only squaks were an Inop. Angle of attack indicator that was cured once I found that the soldered connection at the switch had broken off from a little too much abuse and re positioning. (I love my AOA and don't like being without it) it is the Advance Avionics Sport model. I am happy to hear Betty saying" angle angle push push" as I take off and land
The other one was a too low idle speed. Gave the throttle stop a half turn in between flights, problem solved.
I am very happy with how well everything is working. I instrumented to measure differential pressure between the top of the engine and behind the engine. I use aquarium stones on the ends of cheap tubing and a 0" -15" water column Magnehelic pressure gauge. High side centered at the engine lift thingy, the low side behind the engine in what I assume is a fairly dead air zone.
At around 160 knots, 4,500', OAT around 50F I always see more then 10" differential. If I open my EZ cool cowl flaps it goes up above 13". Very happy with those results. I put extra effort into sealing up the leaks. I would love to hear what others have measured!
It has been my experience that radiators, intercoolers, and oil coolers work well at around 6 or 7 inches differential, so seeing over 10" and low CHTs during break in has me smiling.
CHTs are not an issue at all. Cyl 1 293, 2 301, 3 316, 4 310, all in F.
They pretty much kept that spread and did not very much as long as I kept the mixture full rich. The air dams are still at full height. Maybe I need to add some aluminum tape also to even things out. Glad I did not cut them down ahead of time like I was tempted to do.
The engine was sucking up over 16 GPH at 25 square. Just following the break in instructions that came with the engine, which basically amounts to fly it like you stole it! As I accelerate out on the runway and go to full rich I can hear the engine note go down a notch and I suspect I will see even better performance once I can start leaning it a bit. I am taking off from 4500'. The instructions from Aerosport and other reading says to leave it full rich as long as the engine is running clean. It is not missing or anything but I know I am way rich of best power mixture.
My oil cooler, the legendary 8432R, is really working great. It is on the firewall with a modified RV10 mount and 4" scat feeding it, also have cable operated 4" valve. I could close the valve and watch the oil temps climb up to 220F or so, then just crack the valve open and pretty much put the oil temp anywhere I want it. I kept it close to 200F so far.
On the last flight of the day I began to notice some vibration that I suspected was the pilots side muffler making contact with the cowl. Clint at Vetterman already made a change to my Trombone system, but I obviously need a little more clearance. For now, I ground away the honeycomb where the contact marks were and laid some reinforcement glass layers there, giving it a bit more clearance. Hopefully that will allow more flying and getting the engine broken in, but I may have to send the header back to Clint for another modification. Have to check to see if the engine is settling in the mounts any but it appears that the spinner is nicely fitting to the cowl like I set it up.
Overall I am a happy camper and certainly look forward to more flights tomorrow, maybe even get past my 5 hour phase 1 period after a truly major alteration..
Thanks again for all the ideas of things to look for on first flights. I probably should have checked my idle speed more carefully on the ground before first flight but it did not create any problems.
Randall in Sedona
RV smile is on again after a full time four month full time effort on the engine install.