High Alt. Ops w/A-65 Non-adj Carb..
Tue Jan 14, 2025 7:02 am
High Alt. Ops w/A-65 Non-adj Carb..
We would like to overfly Yellowstone this summer....but we have a Taylorcraft with the non-adjustable carb. I have seen some reports of plug fouling at higher altitudes in the A-65 and was wondering if switching-out the carb for an adjustable model would be a good idea. The lowest altitude you'd have to fly would be about 9600' (Yellowstone has a minimum overfly altitude of 2000'AGL, 9600' would be the lowest you'd have to fly and that's over Lake Yellowstone). Any thoughts or experience others could share about this would be great. (*Note: All my friends have already teased me to get a different airplane for this type of thing...I will take a winning Powerball ticket in lieu of advice...)
Tue Jan 14, 2025 12:06 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
Yes, it is always good to have mixture control.
DENNY
DENNY
DENNY
Tue Jan 14, 2025 2:16 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
I live in Bozeman, MT, just north of Yellowstone. And, yes, the Yellowstone Plateau is pretty high. That said, the Park Service's 2000 foot SUGGESTION is NOT a regulation, but rather a "request". None of which matters much with reference to the carburetor in question.
I am NOT an expert on carburetors, but my former plane was a PA-11 with a C-90. It was equipped with a Marvel Schebler carburetor, with the mixture control functional. i had that plane as high as 14,500 ft (with a little assist from breezes) and never had any issues. On a trip home from Johnson Creek once, I flew next to a gent in another 11, same engine, but with the Stromberg carburetor.....no mixture control. We ran at about 9,500 msl enroute, and he didn't indicate any issues.
I can't speak for a 65, but the TCraft is a light fluff ball, so as long as you're patient, should work fine.
One way to tell: Get in your plane, and climb up to 9500 and see what happens. My guess is it'll run just fine. Could it be better with mixture? Maybe. I am a fan of Marvel carbs, vs Strombergs, but both been around forever.
MTV
I am NOT an expert on carburetors, but my former plane was a PA-11 with a C-90. It was equipped with a Marvel Schebler carburetor, with the mixture control functional. i had that plane as high as 14,500 ft (with a little assist from breezes) and never had any issues. On a trip home from Johnson Creek once, I flew next to a gent in another 11, same engine, but with the Stromberg carburetor.....no mixture control. We ran at about 9,500 msl enroute, and he didn't indicate any issues.
I can't speak for a 65, but the TCraft is a light fluff ball, so as long as you're patient, should work fine.
One way to tell: Get in your plane, and climb up to 9500 and see what happens. My guess is it'll run just fine. Could it be better with mixture? Maybe. I am a fan of Marvel carbs, vs Strombergs, but both been around forever.
MTV
Tue Jan 14, 2025 3:02 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
mtv wrote:I live in Bozeman, MT, just north of Yellowstone. And, yes, the Yellowstone Plateau is pretty high. That said, the Park Service's 2000 foot SUGGESTION is NOT a regulation, but rather a "request". None of which matters much with reference to the carburetor in question.
I am NOT an expert on carburetors, but my former plane was a PA-11 with a C-90. It was equipped with a Marvel Schebler carburetor, with the mixture control functional. i had that plane as high as 14,500 ft (with a little assist from breezes) and never had any issues. On a trip home from Johnson Creek once, I flew next to a gent in another 11, same engine, but with the Stromberg carburetor.....no mixture control. We ran at about 9,500 msl enroute, and he didn't indicate any issues.
I can't speak for a 65, but the TCraft is a light fluff ball, so as long as you're patient, should work fine.
One way to tell: Get in your plane, and climb up to 9500 and see what happens. My guess is it'll run just fine. Could it be better with mixture? Maybe. I am a fan of Marvel carbs, vs Strombergs, but both been around forever.
MTV
^ that
Also if you play with the winds with that big wing on that little plane, it’ll probably give you a good hand getting up to altitude
My A65 doesn’t have mixture, only had it up to 6k ish, but I don’t have much of a doubt it could do its advertised 12.5 ceiling if I really want to (and took my time)
Out of the continental manual, there is no separate chart for the different carbs and both are listed on the TCDS
Scroll down on this site under technical, lots of info on the stromberg carb and adjustments that can be made if needed, including this cool one on adjusting the carb float.
http://www.bowersflybaby.com/tech/fenton.html
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- NineThreeKilo offline
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Tue Jan 14, 2025 3:31 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
What has been said pretty much covered it; you shouldn’t have a problem. The auto lean feature on the Stromberg carb actually works pretty good.
Flew my C85 Luscombe all over near Yellowstone. 9600 feet was a typical cruise altitude. Winter time is a nice time to fly over Yellowstone. Less people around to potentially complain should get a little low, things look different with a blanket of snow, but it is remote so plan to freeze to death if you lose an engine or something.
Flew my C85 Luscombe all over near Yellowstone. 9600 feet was a typical cruise altitude. Winter time is a nice time to fly over Yellowstone. Less people around to potentially complain should get a little low, things look different with a blanket of snow, but it is remote so plan to freeze to death if you lose an engine or something.
Tue Jan 14, 2025 4:36 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
whee wrote:... but it is remote so plan to freeze to death if you lose an engine or something.
Thanks to all for the info....and the advice (*gulp*). Potentially freezing to death in the Taylorcraft might actually happen at altitude as well, given my experiences with my carb heat: Hot toes and cold ears is what I tell passengers in the winter. It's all part of the experience...
Wed Jan 15, 2025 11:19 am
Re: High Alt. Ops w/A-65 Non-adj Carb..
Greetings,
I fly an 1946 A65 BC-12D and I think the answer is "it depends". I recommend taking the aircraft up to altitude where you are now and keep track of weight, density altitude etc. and test it out so you know what to expect with your aircraft. I assume by "no-mixture" carb you are talking about a Stromberg (sp?) wherein someone in it's past decided to just wire the mixture to full rich on the carb and remove the control from the cockpit. That is a common modification by those who don't know better (and spend all their time below 8000'). That's too bad since it works great but it does work differently than the more common controls. Are you running an "as-original" A65? That also matters. Many A65s out there, including mine, have been overhauled with acceptable alternate parts that leave it with a bit more umpf than the original.
My T-cart has been to all the high peaks in Colorado and, on good days (which are the only ones in which I'll take it into the mountains), it has no trouble getting to 14,500'. It does take a while and, often, there is lift to be worked which speeds it up and it's easier to get higher (bring your O2). Keep in mind though, that my A65 is a strong one and I still have the mixture control from my Stromberg (which I rarely use below 10,000 density altitude). Also keep in mind that I'm a light guy by modern standards and I don't carry more than 12 Gallons of gas when I go.
I fly an 1946 A65 BC-12D and I think the answer is "it depends". I recommend taking the aircraft up to altitude where you are now and keep track of weight, density altitude etc. and test it out so you know what to expect with your aircraft. I assume by "no-mixture" carb you are talking about a Stromberg (sp?) wherein someone in it's past decided to just wire the mixture to full rich on the carb and remove the control from the cockpit. That is a common modification by those who don't know better (and spend all their time below 8000'). That's too bad since it works great but it does work differently than the more common controls. Are you running an "as-original" A65? That also matters. Many A65s out there, including mine, have been overhauled with acceptable alternate parts that leave it with a bit more umpf than the original.
My T-cart has been to all the high peaks in Colorado and, on good days (which are the only ones in which I'll take it into the mountains), it has no trouble getting to 14,500'. It does take a while and, often, there is lift to be worked which speeds it up and it's easier to get higher (bring your O2). Keep in mind though, that my A65 is a strong one and I still have the mixture control from my Stromberg (which I rarely use below 10,000 density altitude). Also keep in mind that I'm a light guy by modern standards and I don't carry more than 12 Gallons of gas when I go.
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Wed Jan 15, 2025 1:56 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
anotherstevest wrote:… I assume by "no-mixture" carb you are talking about a Stromberg (sp?) wherein someone in it's past decided to just wire the mixture to full rich on the carb and remove the control from the cockpit. That is a common modification by those who don't know better (and spend all their time below 8000')….
Not exactly true, you’d need to pull the TCDS on the plane and then the engine
Many/most A65 strombergs never had mixture control, frankly in some of these smaller engines it wouldn’t do too much anyways, my guess would be with a proper jetted, good needle seated, proper float measured non mixture A65 the plane is capable of reaching its advertised ceiling with a competent pilot
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Thu Jan 16, 2025 9:24 am
Re: High Alt. Ops w/A-65 Non-adj Carb..
anotherstevest wrote:.... I assume by "no-mixture" carb you are talking about a Stromberg (sp?) wherein someone in it's past decided to just wire the mixture to full rich on the carb and remove the control from the cockpit. That is a common modification by those who don't know better .....
Wasn't there an AD that required this?
I've seen so many small continental-powered airplanes with this done,
I have to think it was due to more than just an owner's whim.
Cessna Skywagon -- accept no substitute!
Thu Jan 16, 2025 11:17 am
Re: High Alt. Ops w/A-65 Non-adj Carb..
Not exactly true, ...
No expert here but been flying and learning about t-carts since '86 and I'd not heard your view before.
A quick look at my A65/A75 overhaul manual Publication X30008 ©2011 CONTINENTAL MOTORS, INC. AUG 2011) and it only calls out the Stromberg NAS3A1 and that is the one with the mixture control. Out of curiosity I did some additional digging and found in the August 2019 "Coup Capers" an article titled, "Stromberg Carbs by the Numbers" and in it the following was stated:
The NA-S3A1 was designated to be used with a mixture control...NA-S3B does NOT have a mixture control... There are very few model engines that the "B" carburetor is used on ...
This article (https://www.univair.com/content/strombe ... 5fWe1iIGRh) does have some nice additional info about Strombergs that might be of interest to folk.
So I'm gratified to learn that my original post wasn't completely ignorant. That said, I'm assuming there is also a basis for your view and I'm still learning...
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Thu Jan 16, 2025 12:29 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
anotherstevest wrote:Not exactly true, ...
No expert here but been flying and learning about t-carts since '86 and I'd not heard your view before.
A quick look at my A65/A75 overhaul manual Publication X30008 ©2011 CONTINENTAL MOTORS, INC. AUG 2011) and it only calls out the Stromberg NAS3A1 and that is the one with the mixture control. Out of curiosity I did some additional digging and found in the August 2019 "Coup Capers" an article titled, "Stromberg Carbs by the Numbers" and in it the following was stated:The NA-S3A1 was designated to be used with a mixture control...NA-S3B does NOT have a mixture control... There are very few model engines that the "B" carburetor is used on ...
This article (https://www.univair.com/content/strombe ... 5fWe1iIGRh) does have some nice additional info about Strombergs that might be of interest to folk.
So I'm gratified to learn that my original post wasn't completely ignorant. That said, I'm assuming there is also a basis for your view and I'm still learning...
No bias, got planes with mixture control, got planes without, and I love em all the same
I posted the screen shots of the info I mentioned
Case and point, my champ, stromberg a65, I can tell you 100% it never had mixture because there isn’t even a hole for the cable or knob, as is the case with tons of a65 stromberg 7ACs, as it is with many other planes with that engine and carb combo.
You are correct that it COULD BE ADDED, for whatever it would be worth on that little engine.
Now, the idea that when you see all the stromberg A65s without mixture it’s because some owner took the time and all to deactivate it, that just doesn’t make sense.
If one never wanted to use mixture they’d just simply not pull the knob.
Again many of these planes don’t even have the holes in the panel, firewall, etc for the mixture cable and controls in the first place
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Thu Jan 16, 2025 12:55 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
Can anyone give me a rundown on just how the automatic mixture control referred to works?
Thu Jan 16, 2025 1:11 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
I'm getting all "MIX-tured" up by this thread.
Thu Jan 16, 2025 3:03 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
Nothing to add here other than a video I stumbled upon going down the YouTube rabbit hole. I do have a A65 with no mixture but have only had it to 6,000ish and that was with help from the Green Mts. And a west wind.
Pete.
https://www.youtube.com/watch?v=opFMUCrRtSU
Pete.
https://www.youtube.com/watch?v=opFMUCrRtSU
Fri Jan 17, 2025 11:41 am
Re: High Alt. Ops w/A-65 Non-adj Carb..
NineThreeKilo wrote:anotherstevest wrote:Not exactly true, ...
No expert here but been flying and learning about t-carts since '86 and I'd not heard your view before.
Again many of these planes don’t even have the holes in the panel, firewall, etc for the mixture cable and controls in the first place
Actually, the absence of a hole in the instrument panel or a knob doesn't indicate anything other than that the AIRCRAFT manufacturer chose not to install one. The engine's carburetor may in fact have been equipped with a mixture control, which was wired to rich by the manufacturer of the airframe. I've seen those on little Continentals.
MTV
Fri Jan 17, 2025 3:50 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
shorton wrote:Can anyone give me a rundown on just how the automatic mixture control referred to works?
http://www.bowersflybaby.com/tech/stromberg_mixture_secrets.pdf
Fri Jan 17, 2025 4:21 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
NineThreeKilo wrote:
Not exactly true, you’d need to pull the TCDS on the plane and then the engine
Many/most A65 strombergs never had mixture control, frankly in some of these smaller engines it wouldn’t do too much anyways, my guess would be with a proper jetted, good needle seated, proper float measured non mixture A65 the plane is capable of reaching its advertised ceiling with a competent pilot
What type certificate are you using??? This sure isn't A-696, which covers most BC series..... this looks more like an aircraft spec sheet and not anything current, therefore not applicable to this at all.
John
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Fri Jan 17, 2025 4:52 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
hardtailjohn wrote:NineThreeKilo wrote:
Not exactly true, you’d need to pull the TCDS on the plane and then the engine
Many/most A65 strombergs never had mixture control, frankly in some of these smaller engines it wouldn’t do too much anyways, my guess would be with a proper jetted, good needle seated, proper float measured non mixture A65 the plane is capable of reaching its advertised ceiling with a competent pilot
What type certificate are you using??? This sure isn't A-696, which covers most BC series..... this looks more like an aircraft spec sheet and not anything current, therefore not applicable to this at all.
John
Few different sources of data, very applicable, gotta read the whole thread
Started off with will a non mixture adjusting stromberg A65 be able to do the OPs flight
Then someone said the strombergs without mixture are due to owners removing the mixture adjustment ability of their planes, which is not really the case in the majority of these aircraft
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Sat Jan 18, 2025 7:57 pm
Re: High Alt. Ops w/A-65 Non-adj Carb..
For the record I have the Stromberg carb, it has the mixture arm on the carb which is safety wired open and my Taylorcraft does not have a provision (either in the firewall or on the inst panel) for the mixture control. My A&P (who is also a vintage airplane judge for EAA Airventure every year) adds to the conversation here when he told me that some carbs have the mixture arm on the carb body but sometimes do not have the mechanical leaning mechanism inside...or sometimes they don't even have the arm on the outside and will have a little cover there. I have also heard others say there is no "Auto-Lean" feature, but I can't speak to that. I've had the Taylorcraft (does anybody call it a Twosome or a Traveller?) up to 6500' here in Wisconsin but plan to take it higher to see what happens. I am curious to look at the plugs for signs of a rich mixture when I do. The one good thing about going to someplace like Yellowstone is that the closest airport I would depart out of (Cody, WY) before hitting the Park is already 5100', so I'd be halfway there altitude wise, right? 
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