SonexBuilders.net

Scott Todd wrote:The Aeroinjectors can be too rich at the low end....that fuel line looks pretty small. Is it gravity feed or is there a pump?

Hi Scott,
That was helpful and it seems that might be what I'm experiencing "loading up" since I can't repeat it after it happens once it then clears. I too, aggressively ground-lean then go full rich on take off. Something I've been doing behind Lycomings for years.

The fuel line is 3/8" from tank to gascolator to FT60 (transducer) then 1/4" (or 5/16") from there. It gravity feeds at 11 gph with full tanks then reduces to 10 gph at 2 gallons of fuel.

So my next step will be to determine for certain what EGT drop I get from peak (or rpm decline).

I have an MGL XTreme and one of the few things that bothers me is the slow response on some of the sensors. When leaning, I move the mixture and have to wait several seconds to see a change. Its a bit frustrating but workable. The fuel flow is about as bad.

Keep us posted on your progress :)

Scott

Scott Todd wrote:I have an MGL XTreme and one of the few things that bothers me is the slow response on some of the sensors. When leaning, I move the mixture and have to wait several seconds to see a change. Its a bit frustrating but workable. The fuel flow is about as bad.
...
Scott

Scott, That is exactly my problem as well. I have the new MX1 and the EGT response is so slow that it is only usable for minor adjustments at cruise (which I've not yet done). I'll reach out to MGL and ask about this - not that it will make any difference.

pappas wrote:[snip]... the engine runs fine upon advance of throttle until just prior to WOT and then stumbles. If that happens, the manual tells us to limit the throttle's ability to advance just a bit prior to the symptom occurring.[snip]

The stumble is not related to too much airflow at full-open, but rather too much fuel. That last 1mm of throttle travel only increases the area of the throat by 1%, but because the needle is pretty much a straight taper you get a full dose of fuel during that same 1mm travel. This can easily be verified by leaning the mixture knob when the engine stumbles during that last 1mm and watching the engine smooth out. Limiting the travel prevents the worst of the situation by eliminating that last 1mm or so. It's simple and effective, or you can just pull the throttle back slightly and accomplish the same thing.

Jeff

Q: 32mm vs 35mm?

But first...
It's been many months since I started this thread and only recently have I figured out what has been going on with this RevFlow revmaster carb. It was running too lean at full throttle and too rich at all other settings. Tuning richer only made things worse. Turns out that the mixture lever, which turns a brass screw to close off the fuel line to the carb, does not have enough travel to allow full idle-cut-off and full-throttle fuel flow at the same time. One (poor) solution is to adjust the linkage so that there is plenty of fuel flow for max throttle but then use the fuel-tank shut-off to kill the engine. I did just (yesterday) perform another linkage mod (recommended by RevMaster) and I'll see if it works in the next day or so.

In the long run I'll likely purchase an AeroInjector. It seems to be more mature and better supported than what I have. But what size? The Revmaster R2300 is an 85HP rated engine and the RevFlow measures slightly larger than 35mm. However the AeroInjector comes as 32mm (30-90hp) and 35mm (90-125hp). Do you those of you, who know, think that the 35mm AeroInjector would cause issues with the R2300?

because the needle is pretty much a straight taper

Actually, not the case. The 4 needles I have for the Aeroinjector all stop the taper about 5/32 from the end. Presumably to eliminate the overly rich condition toward the end of the slide travel.
Didn't work for me. I suspect the orifice varies in diameter from carb to carb thus screwing with the mixture on a case by case basos at WOT.

Mine runs good at WOT. What am I doing wrong?

Bryan Cotton wrote:Mine runs good at WOT. What am I doing wrong?

Your "what" runs good at WOT (32mm, 35mm, revflow)? Your signature indicates aerovee so I'm guessing you have a aeroinjector.

BRS wrote:

Bryan Cotton wrote:Mine runs good at WOT. What am I doing wrong?

Your "what" runs good at WOT (32mm, 35mm, revflow)? Your signature indicates aerovee so I'm guessing you have a aeroinjector.

Aerovee, aeroinjector. My fault, I read everybody's posts and assumed we all did.

BRS wrote:Q: 32mm vs 35mm?
In the long run I'll likely purchase an AeroInjector. It seems to be more mature and better supported than what I have. But what size? The Revmaster R2300 is an 85HP rated engine and the RevFlow measures slightly larger than 35mm. However the AeroInjector comes as 32mm (30-90hp) and 35mm (90-125hp). Do you those of you, who know, think that the 35mm AeroInjector would cause issues with the R2300?

Link to the AeroIjector manual: http://www.aeroconversions.com/support/instruction_sheets/AeroInjector_Manual.pdf

On page 3 they list different engine types and the recommended AeroInjector size. They don't mention your engine. They do suggest contacting Sonex tech support for other recommendations. So email them. I'm sure they get back in a few days.

The AeroInjector manual has a procedure for tuning. This has worked great for many, many builders. However, I've had better success (three different AeroVees) using the procedures described here: http://sonex604.com/aerocarb_thoughts.html As always your milage may vary. Study both methods then pick the one you think works best for you.