I agree with Joe here. No reason you should have to use carb heat especially once the engine is warmed up. Even my little 65 with the Stromberg and no accelerator pump will rev once the engine has been warmed some. In really cold weather, I leave the primer out a bit to richen the mixture until things warm up. I suspect something was missed during the carbureator rebuild, probably a clogged or somewhat restricted passage. Not familiar with the 235 engines but it definitely doesn't sound 'normal'.
Mike Berg
Carb heat cable & mid-range engine stumble
carb stumble
Interesting that this topic should pop up. I flew my C85 / Stromberg equipped Champ yesterday (for the first time in a couple of months) and the engine would stumble when I advanced the throttle between 1700 + 1800 rpm. It runs smooth on either side but does not make the transition smoothly. It doesn't stall, it just stumbles a bit. It is noticeable on takeoff and when power is applied on a touch and go.
I had one sticking valve repaired last year. Do you think my problem is likely carburetor or???
Tim
I had one sticking valve repaired last year. Do you think my problem is likely carburetor or???
Tim
CFII
Champ 81L
Champ 81L
Tim,
My guess would be carb.
From idle to 1700-1800 "or so" the idle circuit system feeds the engine.
From 1500-1800 "or so" the main circuit system feeds the airplane.
They overlap and the carb is designed to do this.
My guess is that your float level might be a bit low, or something restricting part of the idle system. Once past this RPM point it runs fine and is running alone on the "running circuit system" and not both.
Remember that this advise is worth what you paid for it!
Joe A
My guess would be carb.
From idle to 1700-1800 "or so" the idle circuit system feeds the engine.
From 1500-1800 "or so" the main circuit system feeds the airplane.
They overlap and the carb is designed to do this.
My guess is that your float level might be a bit low, or something restricting part of the idle system. Once past this RPM point it runs fine and is running alone on the "running circuit system" and not both.
Remember that this advise is worth what you paid for it!
Joe A
Tim,
If you're using auto fuel be advised that it is only good for about a month or two before it starts forming gum in carbs. Run some avgas through it and see if it doesn't improve operations. I just did this and it made a big difference.
Today's auto fuel is junk. Older auto fuel would last for years and even smelled good.
If you're using auto fuel be advised that it is only good for about a month or two before it starts forming gum in carbs. Run some avgas through it and see if it doesn't improve operations. I just did this and it made a big difference.
Today's auto fuel is junk. Older auto fuel would last for years and even smelled good.
Gus Causbie
Ash Flat, AR
N83564, 7AC-2235, A65-8
Ash Flat, AR
N83564, 7AC-2235, A65-8
Gus,
Without starting another long thread that's been discussed before, I respectfully disagree with you. I've been using auto as my primary fuel for over 25 years in both my Cherokee when I owned it and my Champ with zero problems. Part of the reason being I'd have to fly 20 miles north every time I want to fuel up. Whereas, it's easier (and cheaper) to go to my local Cenex station and buy their premium fuel that doesn't contain ethanol. By the way, I just tested my last tank and it was 'ethanol free'. My tractor, mowers and my Champ sit all winter and start and run just fine. Hot weather/cold weather it doesn't seem to make a difference.
I suppose it's possible to get a bad batch of fuel but it's never happened to me. I do use some 100LL on occasion when it's convenient to fuel up.
Mike Berg
Without starting another long thread that's been discussed before, I respectfully disagree with you. I've been using auto as my primary fuel for over 25 years in both my Cherokee when I owned it and my Champ with zero problems. Part of the reason being I'd have to fly 20 miles north every time I want to fuel up. Whereas, it's easier (and cheaper) to go to my local Cenex station and buy their premium fuel that doesn't contain ethanol. By the way, I just tested my last tank and it was 'ethanol free'. My tractor, mowers and my Champ sit all winter and start and run just fine. Hot weather/cold weather it doesn't seem to make a difference.
I suppose it's possible to get a bad batch of fuel but it's never happened to me. I do use some 100LL on occasion when it's convenient to fuel up.
Mike Berg
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Nathan K. Hammond
- Posts: 2371
- Joined: Wed Nov 17, 2004 00:22
- Location: Danville, KY (DVK)
- Contact:
Tim, I'd say fly it some more. No scientific reason, but little nagging things like that develop from sitting for a while seem to go away after you but some time on the airplane.
I pulled the Cub out over the weekend; it hasn't flown in about 6-7 weeks and the darn thing wouldn't idle. Anything below 800rpm and it would roll back and die. Did a ground run to full power and all checked out, so flew it hard for an hour and all cleared up. Go figure.
nkh
I pulled the Cub out over the weekend; it hasn't flown in about 6-7 weeks and the darn thing wouldn't idle. Anything below 800rpm and it would roll back and die. Did a ground run to full power and all checked out, so flew it hard for an hour and all cleared up. Go figure.
nkh
7AC-5691
Super 85-12F @ DVK
Super 85-12F @ DVK
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Roger Anderson
- Posts: 419
- Joined: Tue Nov 23, 2004 22:22
- Location: Murfreesboro, Tn.
- Contact:
There can occasionally exist a problem that seems to have no solution, at least one that can be found. I had an Ercoupe several years ago, C85, Stromberg. After starting and until fully warmed up, at idle and trying to give it throttle, it would cough, sputter, backfire, hesitate, etc.....unless carb heat was out. Then it was fine. It was also fine after fully warm. Obviously we thought carb problem. That carb was off 3 times and became the most clean, best adjusted carb in the US, work being done by my dad (the carb expert) and our local A&P (the legal expert). We also checked extensively for air leaks around the carb or intakes. WE adjusted mixture. We dedicated our lives to trying to find the problem.
When I sold the Ercoupe, I explained the issue to the buyer, saying use carb heat when taxiing and until throttle is full open on takeoff. He said ok and flew happily away. I wonder if anyone was ever able to find the issue. We sure tried.
When I sold the Ercoupe, I explained the issue to the buyer, saying use carb heat when taxiing and until throttle is full open on takeoff. He said ok and flew happily away. I wonder if anyone was ever able to find the issue. We sure tried.
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twosevenleft
- Posts: 34
- Joined: Sun Mar 01, 2009 13:29
- Location: Sequim WA
- Contact:
My Champ (C65-Stromberg) behaves just like this, worse in the cold weather, not so bad in summer. The carb has been stripped and cleaned etc by an A&P who seemed to know what he was doing. (How do you tell?). I think stuff like this is just part of the character of old airplanes, you have to accept it and enjoy the flying regardless.
JLP
JLP
Stumble
I've only run 100LL. Can't get autofuel without alcohol in my area. I'm going to run it some more before I get too crazy.
Thanks for all the good suggestions...
Tim
Thanks for all the good suggestions...
Tim
CFII
Champ 81L
Champ 81L
I can accept a lot of things because of the fact that my airplane is more than 63 years old. One thing I will not accept is having it cough and sputter when I apply throttle to lift off a frozen lake, and end up sticking it in the trees because of it...
I dropped the plane off last night with the mechanic, and he is going to install a different MA-3A carb that he can confirm that the carb is the culprit. From there, he said he would either try some different jetting, or I'll just take the carb back to the shop that went through it, and have them give it another look.
Now I just need this damn volcano to quit spewing ash all over SouthCentral Alaska, so I can go flying !!!
Hasta ~
Bob K.
Anchorage, AK
I dropped the plane off last night with the mechanic, and he is going to install a different MA-3A carb that he can confirm that the carb is the culprit. From there, he said he would either try some different jetting, or I'll just take the carb back to the shop that went through it, and have them give it another look.
Now I just need this damn volcano to quit spewing ash all over SouthCentral Alaska, so I can go flying !!!
Hasta ~
Bob K.
Anchorage, AK
MikeB,
I think you misunderstood my post. I didn't say not to use auto fuel in aircraft engines. Quite the contrary, I've used it since 1979 in all my airplanes except my fuel injected Navion Rangemaster.
What I was saying is that auto fuel is no longer stable during storage like in the old days before unleaded when it would keep fine for 4-5 years. It may be more stable in colder climates but in our area it is only good for about two months before it becomes stale. It is easy to tell stale gas because it really stinks.
When it is stale it will gum up carbs. I have a bunch of antique vehicles and this is one of my biggest problems along with hyd brakes.
I always use regular, never tried using premium but don't see why that would make it more stable. Maybe Cenex is different, this is a mystery to me??
I often mix avgas and auto fuel, most of the time actually just because it is convenient and I think a bit of avgas is better for the engine. No scientific basis for that idea though.
I think you misunderstood my post. I didn't say not to use auto fuel in aircraft engines. Quite the contrary, I've used it since 1979 in all my airplanes except my fuel injected Navion Rangemaster.
What I was saying is that auto fuel is no longer stable during storage like in the old days before unleaded when it would keep fine for 4-5 years. It may be more stable in colder climates but in our area it is only good for about two months before it becomes stale. It is easy to tell stale gas because it really stinks.
When it is stale it will gum up carbs. I have a bunch of antique vehicles and this is one of my biggest problems along with hyd brakes.
I always use regular, never tried using premium but don't see why that would make it more stable. Maybe Cenex is different, this is a mystery to me??
I often mix avgas and auto fuel, most of the time actually just because it is convenient and I think a bit of avgas is better for the engine. No scientific basis for that idea though.
Gus Causbie
Ash Flat, AR
N83564, 7AC-2235, A65-8
Ash Flat, AR
N83564, 7AC-2235, A65-8
Gus,
The only reason I use premium is that it's the only auto I can get without ethanol at this point. I'm just hoping the politics doesn't overcome common sense in my area of the woods. I also mix 100LL with auto when I happen to get to a airport where they have it and the price is 'reasonable'. My mowers have been sitting all winter with auto fuel in them but they'll probably run just fine when I start them up. I do dump a little 'Stabl-flow' in before I shut them down for the winter.
I know how the STC reads but I have a hard time understanding how it (ethanol). will affect the fuel system on our 'simple' airplanes. Everthing else I own including my old "H" Farmall seems to run just fine on 10%. I did use some E85 in my 'flex fuel' Ranger pickup and it seems to run OK. It may have lowered the mileage slightly but that's about it. I think gasoline has about 95,000 btu's per gallon and ethanol is around 75,000 btu's per gallon. Number 2 diesel is about 140,000 btu's per gallon. If I could only get the Champ to run on #2 diesel..............
Mike Berg
The only reason I use premium is that it's the only auto I can get without ethanol at this point. I'm just hoping the politics doesn't overcome common sense in my area of the woods. I also mix 100LL with auto when I happen to get to a airport where they have it and the price is 'reasonable'. My mowers have been sitting all winter with auto fuel in them but they'll probably run just fine when I start them up. I do dump a little 'Stabl-flow' in before I shut them down for the winter.
I know how the STC reads but I have a hard time understanding how it (ethanol). will affect the fuel system on our 'simple' airplanes. Everthing else I own including my old "H" Farmall seems to run just fine on 10%. I did use some E85 in my 'flex fuel' Ranger pickup and it seems to run OK. It may have lowered the mileage slightly but that's about it. I think gasoline has about 95,000 btu's per gallon and ethanol is around 75,000 btu's per gallon. Number 2 diesel is about 140,000 btu's per gallon. If I could only get the Champ to run on #2 diesel..............
Mike Berg
Mike,
I've seen gas stations with ethanol in the premium but not the regular?? These differences are interesting to me?
Our pumps have a sign saying the fuel may contain as much as 10% ethanol but I've never smelled alcohol in the regular. The sign doesn't say which of the three grades has ethanol?
I burn it in my Champ and it seems to work fine mixed with the avgas which I get when the airport is convenient. I live close to three airports so avgas is not a problem, the only problem is the price which is now $3.99 and probably on the way up since auto fuel is going up.
I agree that these engines will probably burn anything. At the time they were built auto fuel was 73 octane.
I've seen gas stations with ethanol in the premium but not the regular?? These differences are interesting to me?
Our pumps have a sign saying the fuel may contain as much as 10% ethanol but I've never smelled alcohol in the regular. The sign doesn't say which of the three grades has ethanol?
I burn it in my Champ and it seems to work fine mixed with the avgas which I get when the airport is convenient. I live close to three airports so avgas is not a problem, the only problem is the price which is now $3.99 and probably on the way up since auto fuel is going up.
I agree that these engines will probably burn anything. At the time they were built auto fuel was 73 octane.
Gus Causbie
Ash Flat, AR
N83564, 7AC-2235, A65-8
Ash Flat, AR
N83564, 7AC-2235, A65-8
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flyingfool
- Posts: 302
- Joined: Fri Aug 15, 2008 15:03
- Location: Madison, Wisconsin
- Contact:
I wonder about how old the auto gas is by the time I buy it at the station. who knows how long it sat in the ocean tanker, or the pipeline or the fuel depot let alone how long it sat in the tank at your local corner gas station.
I too buy lpremium but mainly because that is all I can find without Ethanol.
I also mix it 75% auto with 25% 100LL. I do this for three reasons. First is that this get you the same amount of lead as old 80 octane avgas which I think the A-65 was designed to run on. (73 avgas has about the same lead as 80). Secondly I think the lead does more good than just ad octane but rather lubricates the top end. Thridly I think that it will help keep the mixture fresh and not get stale as fast.
Since I fly much less frequently in the winter I may switch over to 100% 100LL in about late October or early November so I don't have to worry about the freshness.
One thing I can report in terms of stale gas is that a 1980 Honda CM 400 motorcycle with 2 year old gas will not start. I Drained the gas tank and the carbs, put new gas in doing NOTHING else and it fired right up! I believe I put stabilizer in the gas tank and ran it through the carbs before I stored it for the 2 years. I didn't think it would be stored that long. Just thought I'd pass along that info.
I too buy lpremium but mainly because that is all I can find without Ethanol.
I also mix it 75% auto with 25% 100LL. I do this for three reasons. First is that this get you the same amount of lead as old 80 octane avgas which I think the A-65 was designed to run on. (73 avgas has about the same lead as 80). Secondly I think the lead does more good than just ad octane but rather lubricates the top end. Thridly I think that it will help keep the mixture fresh and not get stale as fast.
Since I fly much less frequently in the winter I may switch over to 100% 100LL in about late October or early November so I don't have to worry about the freshness.
One thing I can report in terms of stale gas is that a 1980 Honda CM 400 motorcycle with 2 year old gas will not start. I Drained the gas tank and the carbs, put new gas in doing NOTHING else and it fired right up! I believe I put stabilizer in the gas tank and ran it through the carbs before I stored it for the 2 years. I didn't think it would be stored that long. Just thought I'd pass along that info.
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big chief 48
- Posts: 125
- Joined: Thu Nov 09, 2006 23:57
- Location: Duluth MN.
- Contact:
stumble
Just a report of sorts. This November, I took my plane completely apart to paint and refinish. I removed the engine and stored it nose down. I did no maintainance on the engine, as it ran perfect. Upon installation and start up, I now have a significant stumble from 1200-1600 r.p.m. I put mmo in the fuel and still does the same thing. Made my ice fishing trip to canada a little nerve-racking. Makes me wonder what the heck could have changed...will fly another 10-15 hrs and report back.