Prop length

[NorthIdahoAvidflyer 374]

Ive been fighting with temps and feel the 64 inch three blade GSC is not loading the engine enough.  Joey said he is running 70 inch on both his planes. What prop and blade length are you running on your 582 powered airplanes?  

I go from running to cool to to hot with one clip position change.  It’s starting to get aggravating. 

[1avidflyer 1983]

What gearbox and ratio do you have?  JImChuk

[NorthIdahoAvidflyer 374]

B.  2.58 : 1

[NorthIdahoAvidflyer 374]

This is the best readings I get in the richest needle position. One up and EGT’s go to 1200. 

[1avidflyer 1983]

I have used a thin washer that raises the needle about a half a notch worth at times.  What is your static RPM?  JimChuk

[chopndrag 226]

I run a 72" 3 blade warp drive tapered tip with a 3:1 . 

[NorthIdahoAvidflyer 374]

I have used a thin washer that raises the needle about a half a notch worth at times.  What is your static RPM?  JimChuk

My static is 5850. This is where I have to be to keep the EGT's in check. WOT in straight and level flight the RPM's will start at 6100 build to 6450. WOT in climb I 6000.

[nlappos 413]

North Idaho, I think you might try to install bigger carb jets, a bigger richer jet will cool the EGTs. As a quick fix you can raise the needle a bit to get more gas in. It is a real goat rope, but I suspect you are too lean and the prop is not the cause.

[1avidflyer 1983]

Are you sure your tach is accurate?  Different kind of props, but I tried a 64" three blade IVO and 68" three blade IVO on my Kitfox 1 582 with 2.58 ratio.  Couldn't really tell the difference from one to the other.  The two blade Warp taper tip performed way better than either of them, EGTs seemed a little more manageable, but it was not near as smooth.  I would have thought the 64" IVO wasn't near enough prop before I tried it, but it didn't run out of adjustment and worked ok.  Also, do your spark plugs reflect what your EGT gauge is telling you?  They are not always perfectly accurate either.  JImChuk

[NorthIdahoAvidflyer 374]

Thank you nlappos, Right now I am set to the required jetting for my Engine/Altitude. With the needle in the bottom slot I get good temps but still on the cool side. The book says there should be a 50 degree temp change per needle adjustment. I'm seeing more like 150 degrees. One needle position changes everything drastically. Maybe I'm going at this wrong. Maybe I need a bigger Main jet then lean the needle to the desired temps. I have not played with the Main jet because my WOT temps are good which normally means the correct amount of main jet. My problem is in that small range between 6800 and 6000 where I fly 85% of the time.

JimChuk, I have two tachometers. One good quality Rotax Tach and a Tiny Tach. Both are reading the same. I contacted GSC and they recommended the prop I currently have but they said I should be set at 12 to 13 degrees pitch and I'm running 16 to keep things cool. I not getting the RPM's i should either. 

Maybe its time to start from the beginning and resetting the propeller to the desired RPM range and re-jet from there. 

Thoughts?? 

[1avidflyer 1983]

What do the spark plugs say?  I would run it on the ground tied off at the rpm you are trying to see about for a minute or two, and then shut the key off with out touching the throttle.  Pull the plugs and look at them.  If they are black, it's running rich, gray or white, very scary.  Coffee colored is probably about right, but better to err on the rich side a tad rather then the other way.  JImChuk

[NorthIdahoAvidflyer 374]

Jimchuk, to be honest I have not looked at the plugs yet. I will do that tomorrow. I read over some set up guild lines today and ordered one size larger jets. The plan is to reset the needle to the richest setting and fly it like that until the new jets get here. Once they do I’m doing to take one degree out of the prop, rejet and go from there. 

[1avidflyer 1983]

Plugs don't lie. Gauges sometimes do.  JImChuk

[Turbo 162]

As Nlappos indicated, these Bing carburetors are not ideal for airplane use.  I agree.  My approach has been to rig an altitude compensation setup like the one Cowlove came up with, using reduced float-bowl pressure for leaning, then jet the carbs as if I were flying out of someplace near sea level.  Well, actually I am, since the Columbia basin bottoms out just a little above S.L.. Having it set up as if you're flying out of an airport at sea level is important if you ever go into a field lower in density altitude than your home field, as you won't be running too lean on T/O and climbout.   Cowlove's solution used a small, 12V diaphragm suction pump, hooked up to a 100 ohm, (5 watt) rheostat, sucking on all the float-bowl ports, and working opposite a drilled-hole "calibrated orifice", since, even at the roughly1/2 atmosphere vacuum that the pump can generate, it's way too much (like leaning for 18000 ft!).  I'll see if I can find his explanation & pics.  It's freakin' elegant!  The suction pumps are apparently used for certain medical devices and are super cheap.  Mine came from China and cost under $2.00!  I have not flown my plane at altitude using the system yet, but Cowlove shows a panel pic of his Catalina at 13999 ft, indicating 60 mph, and 6000 rpm!  If I lean too much at idle I can easily kill the engine, so I think I'm in the ballpark.

The nice thing about leaning with float-bowl pressure is that it affects all 3 of the carb's circuits.  The Arctic Sparrow leaning system, if I understand it correctly, would leave the Idle and main jets unaffected (and too rich) at altitude.  Even with our planes' awesome T/O and climb performance, having the ability to lean for high density altitude takeoffs (and cruise) makes sense.  Still - too lean means high EGT.

Found Cowlove's post!  It's under "Rotax and other engines"/"Leaning the carbs for altitude - on the cheap" .  FWIW.

Sorry if all this seems tangential.  It's just that this business of setting up for one field elevation seems to me to be too limiting.  

Edited 17 Sep 2018 by Turbo

[Bandit 286]

I have been using the Artic Sparrow mixture control for years and I always thought I could change the mixture at any rpm.