I wanted to post this to make sure that everyone has a good
engine run experience and help eliminate some of the potential you
may have for issues. I feel this is important for many reasons,
but one big one is that I believe that Lycoming has been making a
serious mistake on the engines they're shipping out.
First, this is an important one...
Check your engine data plate. The IO-390 has a timing setting of 20 degrees BTDC. At least on mine it is. In my case, I also am using a Lightspeed ignition, so I had to make sure that when I sent my flywheel to Klaus for drilling, it was drilled for magnets for a 20 degrees BTDC setting.
I've been finding that Lycoming is not properly setting the timing on the engines they're shipping.
Case 1: There is another airplane at our airport who just got a new factory IO-390 in his Mooney. He had high CHT's that went over 400. The mechanics did their troubleshooting and found that the factory had both his mags timed to 23 BTDC. Once they corrected that his CHTs dropped into the normal range. They warned me and I checked mine.
Case 2: My timing was set at about 22.5 BTDC, so I backed mine down. I had been ground running at 22.5 but before my first flight I made sure it was at 20 BTDC.
Case 3: I warned a fellow RV14 builder about this today, because he experienced most everything I did on my first engine start. He checked his, and found his was at 22.
So that's 3 brand new from factory IO-390's that I've heard first hand about, in the last week, and all of them were off.
Invest in your own buzz box...it will come in handy.
This is simple but... Depending on your engine monitor, and your ignition choices, you may have RPM readings that are off by double or by half.
On my install I read my engine monitor guide and had my Lightspeed input set to the proper pulse per rev so it worked great on the tach but my mag I had set double so the rpm read half....and I had to change that setting. Everyone may have different experiences here due to the variety of igntion and EFIS, but just be aware that it's something you may see.
Regarding the propeller, don't expect it to cycle immediately when you start the engine the first time. You should all be pre-spinning your engine with the plugs out, to start pumping oil before start, but that isn't going to pump enough to fill the prop hub. Also, it won't cycle at low RPM's. I'd suggest getting it over 1800rpm (maybe over 2000) and cycling it 10 or more times. It will take a while, but eventually it will work. If it did not, think back and make sure you pulled the plug out of the engine crank. You need to do plug pull if you want oil to flow to the hub. When you got your engine (if from Van's/Lycoming) it should have had a sheet explaining this.
Here is a pic of the plug installed in the
crankshaft that gets removed for constant speed prop installs
Next, my idle (and the other RV-14's) were both very rough on first engine start. Anything under 1000 and it wanted to die. Above that, on the Lightspeed it was good, but the mag was rough. At higher power it sounded great though.
You need to do the ground lean test and make sure it's set properly. I found if I idled maybe 1200rpm at full rich...let it stabilize in RPM, and then slowly leaned it until it wanted to cut off, I had maybe a 180 rpm rise or possibly more. That's way way too rich! You want 20 rpm min rise but 50 rpm max rise. On the throttle arm is a little star wheel in the middle of the 2 sections. If you look at the arm, it has an "R" with an arrow on it. Turn it the opposite way a couple turns and re-test. Both of my planes were very excessively rich from the factory. It did take me maybe 6 or 8 times in and out of the cockpit and starting before I got this just right. When you are close, even 2 clicks of the detent will make a noticeable change. But when you are done, you will improve your rough running. It may never be as smooth on the mag as an electronic system, especially under 1000, but mine idles well now. Surprisingly the mag drop is also very small and both ignitions run great. It sounded awful before I got done with that. The timing stuff may have helped too.
Here is a pic of the starwheel adjuster on the throttle linkage of the IO-390
Finally, my engine almost hates any priming. If I prime even for one second, let alone 3, the only way to start it is to pull the mixture all the way back with about 1/2 throttle And crank. Then it fires right up and you quickly push the mixture to about mid travel and it runs well. I believe this engine really wants to be totally lean lean on the ground (which is what you should do for ALL engines) but it won't require much for priming.
I do find it runs great at full rich, in-flight, for break-in, so no problems there.
Hopefully all of the above will help you get your engine in shape for an awesome first flight. I had all of the above adjusted and tested before flying and it was super....but before it was all done it sure didn't run as nice. All just the normal engine check stuff...but it makes a difference.