Runnin' Lean

[Dan Mahalak]

Hey all

As we finished my annual, my IA mentioned that the plugs were real clean, as if I was runnin lean. On runup before the annual, carb heat increased RPm instead of reducing, also as indication that I was running lean.

MY IA thinks I need a Marvel Schebler Carb to replace the stromber on the A-65 that I am currently running.

What Marvel Schebler Carb is required, and does anyone have one laying around I could purchase for this flying season? Any help is welcomed.

Happy wheel landings.
Dan

[ROllerton]

BS.

my advice to me:

dont change the carb,

check the float level. very critical.

[NY86]

Re: Runnin' Lean

Originally posted by Dan Mahalak
was running lean.

MY IA thinks I need a Marvel Schebler Carb to replace the stromber on the A-65 that I am currently running.

Find another IA! (OR at least an A&P

No one EVER accused a Stromberg of running lean!

Get it set up right and it'll be fine and you'll be a couple thousand less poor. The fact that the IA made that statement indicates he's NOT the man for the job!

I find there are 3 classes of people when it comes to Strombergs:
1) those that haven't a clue how they work.
2) Those who say they are Junk, probably because they are a subset of group 1.
3) those who understand them and feel that simplicity is elegant.

[CraigH]

I'll agree with you. Other than the fact that the Stromberg on my C140 leaked a little fuel, I loved it. Simplicity at it's finest.

[Dan Mahalak]

help

Living here in a town of 800 year round tax payers, at the end of the road, I have come to rely on the tribe to answer and help me get the most of my tcraft....so okay, I will try to find another A&p?IA within two hours flying time.....But until then

So what can I do to fix it. I am still running lean. I appreciate simplicity, very much. And, I would like to save some more money, so what can a fella do to adjust his float level, and if I am running lean, which I am, then does the float need to rise or sink more?

????????????

[jgerard]

Would it be smart to try flying for an hour or two with the carb heat on and then check the plugs again. Also what type of fuel are you burning? If it's auto gas I hope it's not oxygenated.

Jason

[yerich109]

Also check that the 'mixture plates' are lapped and not allowing air to leak by. My A/I made double sure that mine fit well together. And make sure it is wired shut when your finished.

I don't know for sure, but there may be other places in the intake that additional air could come in and make the engine run a little lean.

Blue Skies,

[Goneflyin]

Check the hoses and clamps on the intake tupes. the clamps tend to loosen and the rubber on the tubes tends crack from auto gas. I had very similar symptoms, stumbled coming off idle, rough in the 1500-2000 rpm range and would smooth out with carb heat or cracking the primer. My neighbors champ went through a set of hoses in just over 2 yrs.

Bill

[Ron Greene]

Runnin Lean

Found the stromberg articles on the following website, look under Technical Help:

http://www.bowersflybaby.com/tech/engines.htm

[NY86]

I know the author of most if not all these articles and I know he's been fuming more than once about the indiscriminate way his work is passed around the internet. Since he has apparently given permission for them to be posted at the above mentioned web site, I suggest we leave it at that, and not further the problem.

[matsuthunder200]

I have a perficty good stromberg carb that i took off my 75hp cont when i sold it. You are more than welcome to have it if you want it. I would have it inspected and yellow taged its been in the bottom of my toolbox for a few years but im shure it will check out fine............ Let me know

[ROllerton]

Stromberg carburetors

Stolen from the Luscombe mail list:


"
Hi all,
I'm posting this for those of you with Stromberg carburetors who are not happy with their operation, or in need of a repair/overhaul shop for it.
I finally got fed up with the poor idle & rich running on our Cub's C-85 last week and took the Stromberg over to a local accessory shop in Rockford, IL. for what I thought would be a float level adjustment and cleaning.
I briefed "Dan" the Technician who would be working on it, with the specific symptoms that I had noticed: rich idle and a "hesitation" between 1000 and 1200 RPM during when advancing the throttle.
He called me the next morning a said it would be ready later that day. Here's what he found:
1) the main air bleed jet was the incorrect size - too small. 2) the idle air bleed was blocked with crud. 3) the float travel was not correct- about half of what it should have been. 4) the float was leaking - had a small amount of fuel in it. 5) the mixture control plates were gunked up with fuel & oil residue- strange findings as this area should only see air.
Installed the carb on Sunday and we are delighted with the results of the repairs. Idle was clean and the engine ran, to quote a friend, "like a pickle seeder". The throttle response was turbine smooth, without a hint of hesitation or richness. I'm could not be happier with the performance!
The shop is Aircraft Systems, Inc., in Rockford, IL. Phone: (815) 399-0225. It's a wonderful shop that is very quality driven. Their shop rate is $75/hr, and you can talk to the person working on your stuff!

Looking forward to meeting those of you attending Columbia next week.

Rick
Hampshire, IL (68IS)
Luscombe 8b, N28762
[email protected]"

[ROllerton]

Stromberg carburetors

Also Stolen from the Luscombe list:


"Rick,

The comments about your Stromberg (pre repairs) are not unusual. The
antique device is so incredibly simple that it is ignored and does not
receive the service it should in routine maintenance. It is a fine device.

Common issues. Because they (Stromberg NAS) all Look the same, the various
dash numbers and the innards that change them (venturi size, air bleed &
main jet) are frequently replaced with "what's in the shop" if a repair is
made by a local technician. The assumption is that the different parts are
close, or that their substitution will not make any difference. As you can
attest, that is not a correct assumption.

Mixture control plates are often gunked because they see lots of air (with
dust that deposits). Turbulence and the occasional inverted flight (no not
in a cub!) will then deposit some 80 octane or auto fuel in the 'dust
repository' at the mixture wafers. When this dries, it leaves fuel residue
and dye, which causes the gunk.

You may have learned that regular maintenance and a squawk sheet to be
investigated and solved on a regular basis at the maintenance shop is a good
thing. Some never learn that.

Doug Combs, Aviator and Professional Consultant on aeronautical matters"

[Forrest Barber]

I agree that the Stromberg is the best ; IF maintained properly we have the tools and the 19" test set up. I only do the ones that I work on here. I have one out of a Pietenpohl here now with an A-65-8.
I did not notice any comments on the "suction tube" getting restricted. That is the little tube sticking up when you part the carb. It unscrews with pliers and will sure give you a rough idle if plugged or restricted. ALSO they were best used with 80 Oct. and yes there may be a wee stumble at 1000- 1200 rpm where it switches over from idle circuit to the main jet.....just push right on through that area.....