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Who is flying their aerovee with a carb other than the aerocarb? Although it works I have never been really happy with mine. It runs very rough below 1000 rpm, the needle set screw never wants to lock when I adjust the mixture, the carb always goes rich when pulling g's and if you don't get an immediate start you end up with gas pouring out your cowl right next to the exhaust. In my opinion it is overly simplified as a carburetor and isn't really much more than a controlled leak.

There has to be a better alternative. Anybody running the carb from great planes or rotec? Anything else out There?

Keith
#554

kmacht wrote:...
the carb always goes rich when pulling g's
...

Ahhhh!
Is that what that is?!
I always wondered why the engine sometimes will run rough during high G manoeuvres.

Both my Aerovee's run rotec carbs,,,, a series 1 on one and series 2 on the other. Once you get over the experience of dealing with Paul at Rotec the quality of the product eases the pain of the initial first contact.

Before you rule out the AeroInjector, the problem might be in the setup. Getting the right needle, with the correct tuning, and the other little details right, might be the missing element to get the carb working well. The carb will run over a broad range of mixture settings, but don't take the fact that it's running to mean that your tuning is correct. You might need to spend some more time adjusting the needle. If the mixture runs excessively rich at low throttle settings in order to keep the WOT mixture (and temps) running OK, then it's time to try a larger needle.

Other things to rule out include a clogged (or too small) air filter, a worn out fuel orifice (a problem rarely seen, and only on older carbs), a needle carrier and set screw that aren't keeping the needle position constant, or a mixture arm that isn't opening to at least 45 degrees at full-rich position. Try making one more pass thru the tuning guide (and listen to Episode 7 of SonexFlight) and see if that helps with the troubleshooting and tuning.

http://www.sonexflight.com/7/

Jeff

Jeff,

I recently installed an AeroInjector on my Jabiru 2200 and have flown with it about 10 hours. As you know, the Jabiru manual wants the engine to run quite rich at full throttle to aid in cooling the engine. Doing this results in a very rich mixture at idle. I'd like to follow up on your suggestion to change to a higher needle. Could you take a moment to explain why you made this suggestion? I suspect the steeper angle on the needle provides more fuel at full throttle, and less at idle???

I've only set the #2 needle. I'm very rich at idle, but can lean it with the mixture control. I can get my full throttle EGT to about 1275F. At cruise I can lean to 1350F. But the belly of the airplane is sooty, black.

I noticed a further problem in setting the needle height. When I go to set the locking set screw, it pushes down on the needle assembly, pushing it lean. I've taken to drawing a mark on the needle and looking into the throat of the carb to ensure a relative setting. The concept of an eighth to a quarter turn adjustment is impossible given this action.

I just listened to your podcast on the AeroInjector. Well done. Lots of helpful, confirming information.

Mervin Friesen
Sonex 122

Friesen5 wrote:Jeff,

I recently installed an AeroInjector on my Jabiru 2200 and have flown with it about 10 hours. As you know, the Jabiru manual wants the engine to run quite rich at full throttle to aid in cooling the engine. Doing this results in a very rich mixture at idle. I'd like to follow up on your suggestion to change to a higher needle. Could you take a moment to explain why you made this suggestion? I suspect the steeper angle on the needle provides more fuel at full throttle, and less at idle???

I've only set the #2 needle. I'm very rich at idle, but can lean it with the mixture control. I can get my full throttle EGT to about 1275F. At cruise I can lean to 1350F. But the belly of the airplane is sooty, black.

I noticed a further problem in setting the needle height. When I go to set the locking set screw, it pushes down on the needle assembly, pushing it lean. I've taken to drawing a mark on the needle and looking into the throat of the carb to ensure a relative setting. The concept of an eighth to a quarter turn adjustment is impossible given this action.

I just listened to your podcast on the AeroInjector. Well done. Lots of helpful, confirming information.

Mervin Friesen
Sonex 122

Mervin,

While I cannot answer the question you asked Jeff, I can offer one other thought. I had challenges getting my AeroInjector needle to stay where I set it. I took the threaded mount the needle sits in and slightly flattened/peened the threads with a hammer. Just enough to flatten the threads a very small amount.

Doing so solved my problem immediately.

Just my two cents. Worth far less.

My suggestion is to listen to the SonexFlight podcast on Aerocarb tuning with Kerry.

I recently returned to the Aerocarb after a bad experience with the Rotec, followed Kerry's and Jeff's suggestions and frankly, I am very happy with it. You do need to adjust your mixture depending on whether you are at idle, cruise or takeoff. Its not a set and forget. But its repeatable and you will learn where it needs to be for the phase of flight you are in.

What was the bad experience you had with the rotec? Even with a properly tuned aerocarb you atill.have the issue of it going rich as you pull g's as well as it leaking fuel right above the exhaust if you don't get an immediate start.

Keith
#554

kmacht wrote:What was the bad experience you had with the rotec? Even with a properly tuned aerocarb you atill.have the issue of it going rich as you pull g's as well as it leaking fuel right above the exhaust if you don't get an immediate start.

Keith
#554

Off field landing due to sticky regulator, extremely poor customer service afterwards.
Not sure why you are concerned about momentary richness at high Gs.
As for leaking when you aren't running, yes, it requires you remember to shut off fuel with full lean cutoff on the mixture.

I have 185 hours on my Onex, Aerovee, AeroInjector. The last 100 hours using the #3 needle. I had the same experience as you and others with the #2 and #2 1/2. Great at wot and super rich at idle, requiring a maximum mixture change. We did a significant amount of research, even making a new needle holder and seven needles of our own to solve the problem. As it turned out, #7, unknown to us at the time, was an exact copy of #3. My needles had several problems that made adjustment difficult. First, they were not all the same diameter. Second, the needle holder had too much play in the ball joint. It almost equaled 1/2 turn of adjustment. Third, the wot sweet spot (needle thickness) and the idle sweet spot were not both located within the slide movement, requiring the mixture adjustment.
Tighten up the ball joint any way you can. Try the #3 needle. I have mine adjusted for wot with the mixture about 1/2 inch out. During climb out when temps tend to go high, a small adjustment richer cools things off. Adjusted back to the original setting for cruise. After landing there is no need to touch the mixture, it idles at less than 1000 rpm. I shut down with the main fuel valve so the mixture isn't touched from one flight to the next. It's almost a set and forget.