Normal for an Aeroinjector?

[Area 51%]

My intake was squeaky-clean when it was installed. Great tip though. I even went as far as sandblasting the inside of the pipes. Not to clean them better, but to rough them up a bit to help keep the fuel atomized on it's way to the salt mines.

For the record, I do not have EGT information.

I've been largely fighting myself during this tuning process. As it turns out, it's important to do the test runs with the cowl on the airplane. I've been trying to tune two different engines over the last week. One that's getting fresh/cool air, and one that has to deal with hot/stale air inside the cowl. Runs great without the cowl, runs terribly rich with it on. It boggles the mind how much power loss there must be by sucking hot air into the intake.

The #2 needle went back in this morning, and after a couple of sessions, I was able to get consistent (if not sought after) results. The idle is slightly lean, but acceptable. The top-end is still on the rich side, but can be controlled with a calibrated clothespin between the mixture knob and dash.

Any tips on how to lean the WOT position without affecting the idle would be appreciated. Don't know how comfortable I am trusting my life to a clothespin. I do have a K&N 3120 (I think) air filter on order. I'm hoping it might flow enough extra air at high throttle settings to overcome the rich condition. We shall see.

The ball bearing between the carrier and jamb screw trick has kept me out of the looney bin for the time being.

[Rynoth]

The #2 needle went back in this morning, and after a couple of sessions, I was able to get consistent (if not sought after) results. The idle is slightly lean, but acceptable. The top-end is still on the rich side, but can be controlled with a calibrated clothespin between the mixture knob and dash.

Any tips on how to lean the WOT position without affecting the idle would be appreciated.

I have a hard time believing that you're rich at high power but lean at idle (assuming the mixture knob isn't moved), based on my experience with the aeroinjector. Mine is always more rich at idle than WOT even when running a 3.0 needle. I tune for in-flight/WOT power setting and lean the mixture knob aggressively on the ground at idle.

If I were to anecdotally summarize my aeroinjector tuning experience, it would go something like this:

1) start with the needle lean to the point that the engine will start but sputter out for being too lean (with full rich mixture knob.)
2) enrichen the needle bit by bit until the engine will start and run at idle with mixture knob full rich.
3) go to high power and verify the mixture is rich enough for full power (it will probably still be too lean at WOT)
4) proceed to fine-tune the injector per the manual.

I've just never had an experience yet that the mixture was too lean at idle and too rich at WOT, the opposite has always been true regardless of needle size. If my engine will idle when mixture knob is full rich (even if a bit rough), and run well at WOT full rich, I know I'm close to having the needle tuned.

Disclaimer: I have an Aerovee Turbo, which actually makes this even more complicated as I never actually go WOT for over-boosting the turbo. Makes the fine tuning a bit more complicated, but I don't think it changes the approach to tuning.

[Area 51%]

That's the thing Ryan. It was obviously too rich after re-insertion of the #2 on top end, but idled great. Leaned the needle to help WOT, and the idle started to suffer.

As it stands now, you only have to pull the mixture knob out a half inch and the engine dies at an idle. That is also the sweet spot for WOT.

[NWade]

You say it was "obviously too rich" - but what evidence / data are you using to come to that conclusion?

Watching EGT values change as you slowly pull the mixture is by far the best way to track whether you're rich or lean. But it sounds like you don't have any EGT monitoring?
You can glean some information from your RPMs (they should slightly rise as you slowly pull the mixture knob, then fall again as you pass lean of peak); but its a subtler signal and doesn't give you nearly as much information as an EGT gauge will.

I'm with Ryan on this. I've never seen or heard (or experienced myself) an AeroInjector getting richer at WOT than at idle. The only thing I could think that would do this is a junked-up air filter; or perhaps a lot of sealant squeeze-out partially blocking your intake manifold (where you attach it to the engine heads). These kinds of partial blockages might allow enough airflow at low RPM, but not at high RPM.

Have you checked your secondary ignition timing? (One of the best ways to check this is to go to a mid-throttle setting, say around 2000 RPM, and then turn off the secondary ignition. Then turn it back on and turn your primary ignition off. If you get a major RPM change then your timing is off).

Finally, if you have not read Jeff Shultz's AeroInjector tuning procedure, I highly recommend it as its one of the best and most-complete write-ups with lots of great information. Unfortunately it (like all the others) really works best with an EGT gauge.
http://www.sonex604.com/carb_tuning.html

--Noel
P.S. Jumping back a few posts, regarding the mixture: Read the manual for the AeroInjector. See page 13 - you want the mixture arm to swing through about 90 degrees of travel, from full open to full closed.

[Area 51%]

The "obviously too rich" evidence/data came from the fact that at WOT the engine misfired wildly till I pulled the mixture control out about a half inch. Happy engine at that point till I reduced the throttle to idle. It promptly quit and wouldn't restart till I pushed the mixture back in all the way.

Once again...I have no EGTs.

The engine currently has 1.3hrs ground run time and the air filter is as pristine as it was coming out of the box.

I don't believe in silicone at the intakes as gasoline will dissolve all if not most. I use the stamped steel gaskets as supplied by VW and have tested for leaks multiple times.

As far as my timing goes, I get a change in exhaust note when switching off either mag, but little RPM drop.

The aeroinjector manual doesn't really tell you 90deg of travel. It does say 45deg at full rich. It's only a guess the arm starts at 45deg the other way. That's why I inquired earlier about the actual degrees of travel.

I'm inclined to try a different #2 needle, on the chance the one I have was ground incorrectly.

FWIW..........I too find it odd that it's lean at idle.