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.