Stromberg Mixture Sensitivity

[smmilke]

I read through the overview on Stromberg carbs the other day. There are a few useful things in here, especially if you hand prop. http://www.cessna120-140.org/forum/f...___secrets.pdf On page 4 they mention that the original linkages for the mixture control were too short and this made the mixture very sensitive. I have hardly ever messed with the mixture but I was crossing some mountains the other day at 6500 and as soon as I started to pull the mixture I got a pretty significant drop in rpm. I'm not able to pull it a small enough distance to see a rise in rmp, let alone fine tune things. Does this sounds normal for original linkages? Does the linkage mod really make it that much easier to fine tune the mixture but only doubling the arm length?

Shaun

[M Towsley]

Re: Stromberg Mixture Sensitivity

On the plane I did put the mixture on I never extended the arm. But with the nature of this type of mixture it takes a little time before you see results, hence the reason to move it slowly. The longer arm would undoubtedly help the fine tuning.

[taylorcraftbc65]

Re: Stromberg Mixture Sensitivity

Has anyone here thought of replacing the NAS 3 with a NIB, factory rebuilt MA-3? Here is the link. http://www.aeroinstock.com/products/...ail/index.html

[Guest]

Re: Stromberg Mixture Sensitivity

Has anyone here thought of replacing the NAS 3 with a NIB, factory rebuilt MA-3? Here is the link. http://www.aeroinstock.com/products/...ail/index.html

Good idea.

If heat box and throttle linkage just fit up and plumbing as well then it cheaper than rebuilding at a shop.

Dave

[smmilke]

Re: Stromberg Mixture Sensitivity

I moved the knob as slowly as I could, it was almost as if pulling on it at all would cause the rpm's to drop. 6500 feet isn't too far from the altitude that these the mixture control is supposed to become effective. Is there reason to believe I might have different results even higher up?

[Mark Julicher]

Re: Stromberg Mixture Sensitivity

I cruise around at 2500 feet and if I pull my mixture 1/2 back I see 150 degree increase in EGT. Even then, the A-65 is running at about 1350 degrees, not terribly hot.

[birdlegs]

Re: Stromberg Mixture Sensitivity

I installed an MA3SPA on my C85-8F and never looked back, it requires some tweeks, anyone curious send me a private message for the deatails. B

[taylorcraftbc65]

Re: Stromberg Mixture Sensitivity

The problem that I have here with the NAS-3, is that NONE of these 40's and younger A&Ps has even SEEN one of these Carbs, they only know the Marvels. The A&P that rebuilt mine made it run WORSE. I just want a carb that these young bucks can work on.

[adrozell]

Re: Stromberg Mixture Sensitivity

Some of us have! Started working with them at 19. So don't say "none"

[taylorcraftbc65]

Re: Stromberg Mixture Sensitivity

Some of us have! Started working with them at 19. So don't say "none"

But I bet you don't live near El Paso, Texas.

[adrozell]

Re: Stromberg Mixture Sensitivity

Nope, Near the red river. I am just the odd one. just like hanging around the old guys and learning. Heck evan the old guys don't know the old stuff. I know at A&P school I knew more about the a and c series than the instructors. Everything is geared towards bigger and faster.

To get back on topic mine is wired rich. Never fly so high I need it here in north Texas. Flew a Cessna 120 with the mixture installed, but never got it high enough to use ether. I would like to try it out on a 65 to see if it would be worth messing with on mine. But most I see around here are all wired rich like mine.

[Hank Jarrett]

Re: Stromberg Mixture Sensitivity

Mine works, but I have never used it. Too hard to smell the cut hay if you are high enough to have it be effective. I leave it functional because it doesn't cost anything and some day I might want to climb to cooler air.

Hank

[smmilke]

Re: Stromberg Mixture Sensitivity

I've been doing some flying from the glaciers in the AK range and its easiest to climb to 9K or 10K to get where I'm going. The problem is even at 10K I can ever so slowly move the mixture out a significant distance and never see a rise in rpm before I get a drop and the motor starts running rough. Surely the mixture should be effective at that altitude!? I am still able to make about 2500 rmp (maybe more) but I have a fairly flat prop.

[Mark Julicher]

Re: Stromberg Mixture Sensitivity

I can't say that I have ever seen a rise in RPM when I use my Stromburg mixture, but I do see a rise in EGT.

[smmilke]

Re: Stromberg Mixture Sensitivity

Interesting, is that enough to make any perceptible difference in airspeed? I would assume that if there is no rise in rpm's it's not even worth messing with the mixture.