The Stromberg Mixture Control on the C-85 and C-90, Truths and Tales

[1600vw]

http://www.thestrombergspecialist.com/images/pdfs/articles/stromberg_mixture_secrets.pdf

I found this and wanted to share with those whom may not know about this.

Tony

[rwanttaja]

Other articles about the Stromberg carb written by Neal Wright can be found at:

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

Ron Wanttaja

[1600vw]

Great Post Ron.

I have talked with many a pilot who state a lot of the Myth's that are talked about on the posting I made. The thing about this. Here I am just showing up on the aviation seen a few years ago and now I am trying to show things like this to the old times whom have been doing this or working on things like this for years. With the attitudes of these folks lets just say...Who the yeck am I telling these people anything.

Attitudes like this are not good, Makes me wonder how they ever learned anything.

Tony

[rwanttaja]

Got a Stromberg on my Fly Baby, been working fine. When I run 100LL, I pull the mixture out full while taxiing. If I forget to push it back in, the runup quickly points out that the Stromberg mixture control DOES work.

I've never used it in flight...most of my flying is done at 3000 MSL or lower. Have fiddled with it, verified, again, that it *does* work.

Only issue I have is the "Stromberg Drool"; a very slow drip from it. I put a pan down to protect the hangar floor. Sure, I should pull the carburetor apart, replace needle and seat, lap them, etc. But it works, now, and I'm loath to mess with it.

Though who knows. At the last condition inspection, the A&P had me sign a statement acknowledging he recommended I replace my 50-year-old mags. He'll probably add a line about the Stromberg next year. Eventually, I'll have a whole disclaimer list....

(Good A&P, though, just a bit skittish about liability).

Ron Wanttaja

[Jeff Boatright]

I never could get my C-85 to run well on a Stromberg. Finally went with a Marvel-Schebler and am much happier. No stumbles, no rough-running rpm ranges, and much better fuel economy. I rarely fly above 3000 msl, too, but I've gone from 5-6 gph to 2-4 gph! No question, a Stromberg will suffice, I flew with one for years, but in my hands, it's no where near as good as an M-S.

[rwanttaja]

Jeff, I've never had any real problems traceable to the Stromberg on my own C-85. But I do have an RPM range (about 1800 RPM) where things do seem shakier. I always assumed it was a prop issue (metal prop) but after reading your experience, I wonder if the Stromberg doesn't like that RPM....

An old-time EAA member gave me a box 'o Strombergs a few years back, maybe I'd better dig out a carb or two of the right model.

Ron Wanttaja

[Bill Greenwood]

I fly a '46 Piper J3 Cub with a C-90 engine. The plane does NOT have a mixture control at all, there is no knob on the dash and no cable to pull. It has a Stromberg carb. I don't know if it has any kind of mixture control plate or lever on the carb itself, only that I don't adjust the mixture.
It starts fine, mostly on the first pull if cold, sometimes may take more if it has been run. It idles fine, slow maybe 500 rpm and runs fine, but there is no accelerator pump on the carb so I have to move the throttle slowly , not jam it open or closed.
I live at 7800 feet and have flown the plane as high as 14,000 and as low as 5000 with no mixture change and it seems to run fine, not much power left at 14k but it will go there.

[1600vw]

Bill where do you live? I have lived at 9700' in summit county Colorado. I can not imagine flying an airplane to 14,000'. I just watched a show on aviators about high flying and oxygen deprivation, this would worry me at those altitudes you have flown at.

What size prop do you use at that altitude?

Tony

[Jeff Boatright]

Jeff, I've never had any real problems traceable to the Stromberg on my own C-85. But I do have an RPM range (about 1800 RPM) where things do seem shakier. I always assumed it was a prop issue (metal prop) but after reading your experience, I wonder if the Stromberg doesn't like that RPM....

An old-time EAA member gave me a box 'o Strombergs a few years back, maybe I'd better dig out a carb or two of the right model.

Ron Wanttaja

Hi Ron,

I consistently had rough running between 2150-2250 rpm until I switched to the M-S. I'd also used other Stromberg carbs, but they had their own problems. By and large I was OK with the Stromberg, but I'll never go back now that I'm able to more carefully set the mixture. Heck, I've had severely flights where I've only burned 2 gph! (And yes, I have CHT probes on all 4 cylinders).

[champ driver]

Thanks for the article, I saved it for later when I have more time to read it, although I may already have it in my papers I keep for my Champ.
I've never really had any problems with my Stromberg on my A-75 on the Champ. It will leak after shutdown if I don't turn the fuel off and run the float bowl down for about 30 seconds before shutting off the mags. I've read all I could find years ago about lapping the needle and seat and just couldn't get it to stop dripping after shutdown.
Other than that, it's a great little carb, and yes, my mixture is safety wired full rich. I always seem to burn 4.2 gallons per hour at 2300rpm.
Thanks for posting the article.
Jim

[1600vw]

champ driver: Thanks for the comment. Just trying to help.

Tony

[raytoews]

My first airplane was a Taylorcraft which really taught me to fly.
This discussion got me thinking about shutting down an engine.
I remember the 70's when I was an Auto mechanic, we used to overhaul those cast iron V8 chevy's. There would be so much wear at the top of the cylinder in 100k miles you couldn't get the piston out without a ridge reamer.
I bought an old Datsun with a couple 100k miles and decided to overhaul it. The pistons popped right out, no ridge. I don't know if the Japanese were using better iron, I doubt it because the body rusted out in no time.
That bothered me and I came up with an answer.
When you shut down those old cars you killed the ignition and as the engine wound down it kept dumping fuel into the combustion chamber washing down the cylinder.
The Datsun had a solenoid on the carb which was controlled by the ignition switch. Called an anti diesel valve.
That old Tcart was a serious oil burner and when I overhauled the cylinders they were badly worn.
Cars now shut off the injectors, I haven't overhauled for years but they seem to run forever.
I fixed carbs for a living for a while in the late 80's, I was so glad to see EFI come along.

[1600vw]

When I went and picked up my new airplane, after we started it I shut it off with the mag. The man I purchased her from told me, always shut it off using mixture control. This is a Stromberg carb.

Myself I love carbs, I built me an 671 supercharged 350. I used edelbrock 600 carbs. I used these because they flowed just the amount I wanted at WOT not to rich for my setup and the leaner you can keep this at WOT the better throttle response you have. But the idle circuit was just a little to small for this setup. I took these carbs apart and reworked the idle circuits to get the flow I wanted at idle. Doing this make a real responsive throttle. Better then just dropping a couple carbs off the shelf on the engine.

Fuel injection I was just bolting parts together..What fun is that?

3706

Tony

P.S. this is an S10 pickup

[jethro99]

Bill where do you live? I have lived at 9700' in summit county Colorado. I can not imagine flying an airplane to 14,000'. I just watched a show on aviators about high flying and oxygen deprivation, this would worry me at those altitudes you have flown at.

What size prop do you use at that altitude?

Tony

When in the Navy the pilots of the S2 we crewed in regularly took it to 16,000 feet with the admonition to check your finger nails. If they start to turn blue we will descend. I will never forget one time we were about 15,000 and a crew mate in the back working the camera asked for permission to smoke. Denied. Two puffs and I bet he would have gone out like a light.