Not really sure if this is normal or not. I put a few hours on my new O 520. P ponk. That puts my total time up to about 3 so I really have no idea how it should be. This thing gets carb ice unlike any engine I have ever had. It was 40f on the ground and freezing at a few thousand. Lots moisture around with snow/rain showers in the area that I never got into. On takeoff and climb power at about 2000ft I get a little bit of a shake and rpm had creep so I pull carb heat and he thing about quits then veroom. Carb ice for sure but I was surprised to see it at climb power so soon. I pretty much flew all day with carb heat on. It just seems way more carb ice producing then the 470 ever was. More air more fuel more ice??
Also leaning. Then470 I could leave full rich and never think about it until 6 k or more but it not a big deal even then. The 520 gets to 3000 and starts to get rough and wants to be leaned. Smooths right out with some leaning.

Folks often use partial carb heat with the pponk to help even out the fuel/air mixture, carb air in the low 50s works good to even out the EGTs and CHTs. Added benefit is less carb ice.

PAMR:

Have a 520 in my 180 and it collects ice like no other engine I have ever had. Prior to having a 520 in my 180, had a 470 and there is no comparison. Had almost no ice problems with the 470 and have had significant problems with the 520. If you figure out a cure (other than converting to injection), let us know.

Regards, Larry

Do they use the same carburetor? If so perhaps the vacuum on the induction side of the throttle plate is greater than the 470 because of the extra displacement doing all that sucking.

I dunno. You're prob not looking for uneducated guesses.

I would be checking for an intake leak. I had an O470 that had seemingly wicked carb ice problems after overhaul similar to what you are experiencing. We finally tracked it to a leak on one of the front cylinders or the cross-over (can't remember which it was). Something is amiss but you will find it. Good luck

Never had an O520 but with O470 its been my experience in this ice making climate where I live that it is very possible to get carb ice at any power setting. It seems like the more fresh the carb is, as in freshly rebuilt, the more ice they make. I can only imagine the 520 would make even more due to the increased amount of airflow through basically the same carb.

I learned to fly in dry country and was always instructed that you couldn't get carb ice with climb power. That might be the case in the desert, but it certainly is not when its high humidity and low ambient.

We never leaned our 470's much either but getting above 3K around here is rare.

Why some engines/installations have carb ice issues and others don't is a fascinating subject. In the almost 10 years I've owned my 180 (O-470-K) I've flown all over the country in all seasons and not once had a carb ice issue. I know many folks have had much different experiences with the O-470. I had more carb ice in my Citabria. Go figure.

Thermodynamics is complex!

Are you operating at the exact same manifold pressure that your 470 could without ice? I guess so if you say you're icing at climb power. Definitely seems odd.

Years ago there was an AD on the MS 3SPA that's used on the 170. It had something to do with the venturi being improperly formed or something, and it would cause a flutter that produced vibration (somebody who remembers better can correct me.) My point is that if something so delicate as the venturi shape can cause havoc in the carb, something in your new carb could be producing a condition that's even more prone to ice than before its overhaul.

88h- your experience sounds similar to mine witch is somewhat refreshing. I was considering doing a bendix fuel injection on it before...

Beeman- Intake leak had crossed my mind but I think I have ruled that out. It responds so well to leaning with no backfire or anything. Anytime I have had intake leaks it always runs rough, is barely leanable and usually leaks fuel. I have non of those.

Oregon- seems rare that you would never have much carb ice in the 180. I wonder if you have a air box leak and you are always getting some hot air past the valve?

Halestrom- do you mean a carb air temp gauge?

Zzzzz- maybe you are thinking on the two pice Venturi AD? I have been running same power settings.


So another question. Is carb ice worse or better with car gas? I have only run 100LL but will run car gas in the future.

Another theory. The oil temp has yet to get hotter then 150. I'm going to block some of the oil cooler off tomorrow and see if warmer oil helps.

PAMR MX wrote:
So another question. Is carb ice worse or better with car gas? I have only run 100LL but will run car gas in the future.

As a new pilot I didn't expected to contribute to any discussion for a long time, but I can say from today's studying for my PPL that Mogas is worse for ice than Avgas.

So says 'From The Ground Up', I'm still waiting for personal experience to relay!

Yes, carb temp gauge.


I stopped by Camano Island last week and had a 2 hour visit with Steve Knopp to pick his brain. He is a wealth of information, give him a call. If at first you don't get him on the phone keep trying, it's worth it.

albravo wrote:

PAMR MX wrote:
So another question. Is carb ice worse or better with car gas? I have only run 100LL but will run car gas in the future.

As a new pilot I didn't expected to contribute to any discussion for a long time, but I can say from today's studying for my PPL that Mogas is worse for ice than Avgas.

So says 'From The Ground Up'

Might have to check out that book too see what the explanation is. The C85 in the Luscombe made ice like crazy in certain conditions that were frequent in the spring and fall. I never noticed any difference between mogas and 100LL when it came to carb ice.

I had the Texas Skyways 520 in my 182. Flying around at low power settings doing instrument practice it was likely to pick up ice when temps were cool with high humidity. Always cleared up quickly though. Wish I would have sprung for the fuel injection.

There are a lot of icing charts out there, but here's one, and it's pretty clear that carb ice can form in some situations which are somewhat unexpected:



I've gotten carb ice in Anchorage on a clear, cold day, such that the 150's O-200 Continental quit on short final into Merrill Field. I don't think I've forgotten the carb heat on a Cessna since then. Quite a learning experience for a barely post-solo student!

I've gotten carb ice at Laramie on a cool but dry Fall day in a PA28 Archer with an O-360 Lycoming, such that the amount of available power was significantly less than the throttle setting--learned not to believe Piper's POH's advice to only use carb heat if desired and made it every time the throttle is reduced for landing.

I've gotten carb ice over Nebraska at cruise in a Skylane with a stock O-470, dark night, high clouds, seemingly no significant moisture, solved with just a bit of carb heat.

I've gotten carb ice over northeast Iowa on an 80F cloudless day in early August with my O-360 Lycoming, solved with full carb heat and full throttle.

But with a carb temp gauge in the TR182 I partnered in the late 70s (TO-540 Lycoming), I never got carb ice because I pulled the carb heat on time. Since installing a carb temp gauge on my O-360 Lycoming (part of my Insight G1), I have not gotten carb ice for the same reason.

The key to avoiding carb ice is to apply carb heat soon enough, while the engine is producing enough heat to accomplish the job. If the air coming into the carb throat is a few degrees above freezing, that's the time to pull the carb heat. If it's a lot higher than freezing, or below freezing, there's less likelihood of carb ice. But there aren't any guarantees, so if there's any indication such as rough running or much less power for the throttle setting, regardless of the carb temp gauge indication, pull the carb heat and go to full throttle to melt it out. It's bad stuff!

Cary

A friend of mine has the Pponk in his 180 and was having trouble with icing. he started doing a bunch of research and found that there are a bunch of different sized crossover tubes and yet they all have the same part number. He was lucky enough to have access to a bunch of different sizes so he tried them all and found one that worked well for his package. It seems that crossover tube is almost tuned to the engine. He also installed some of that black pipe insulation they use for refrigeration pipes. These thing made his system work. Another friend has a stock 180 that was ok until he switched to Mogas and then the thing would ice up. He installed the pipe insulation only and that worked for him.

I seem to get a lot more carb ice with the big engine than i ever did before with the 470. I actually hardly ever used the carb heat in with the 470. Now that i almost have 300hr with the ponk, im running it a lot more than i used to. I find myself using it around that magical 70 degree number that was talked about while getting our pilots license.

When i say using it much more i mean, using it at partial settings in cruise flight at lower temps.

(Slap my wrist now) Using it during the landing phase of flight..was actually never learnt to use it in this phase during flight training 1000 hr ago flying fuel injected planes.

I always used to "clear out" the engine before entering the pattern, i did this once in carson city with snow on the ground and thought i was going to lose the engine...now i use it every single time even in 100+ degree weather.

All that being said, i seem to agree with your statements from above.. i see the same thing with mine. I think its the nature of the beast flowing that much more air through the carb and airbox....lots more cubes to supply air to.

Most of the time down here in the central valley i dont rely on it much, and dont need it when temps are high...its also very dry here. But my pponk i feel is very prone to carb ice. I use it tons more than i ever did on the old 470 which people have told me is an ice factory in a C182....I think the ponk is an ice factory in the 182!!!


But i still have that pponk grin


Mike

albravo wrote:As a new pilot I didn't expected to contribute to any discussion for a long time, but I can say from today's studying for my PPL that Mogas is worse for ice than Avgas.

So says 'From The Ground Up', I'm still waiting for personal experience to relay!

Contribute some more.

My experience has been the opposite. I've had fewer icing problems with mogas than avgas (lycoming o-540/b4b5), though I didn't realize that until I read your note above. Did the book say about the physics of why avgas is supposed to be worse?

Any of you ponder what antifreeze(ethanol) in the fuel would do to ice build up in the carb? I believe I remember the article on AGE-85 in the TX Skyways engine saying carb ice was a non issue. I was at the MN Pilots show this weekend and noticed the Kodiak has a tube coming out of the spinner that flows alcohol down the leading edge of the blades.

Carb Ice is a very near and dear subject to me -I've had 2 "precautionary" landings because of it . Both in the 0470 powered 182. Once winter other blazing hot summer. Pretty sure it's because of the Carb Airbox -air intake design location. Car gas makes it even worse - a wisp of moisture 20 miles away will turn instant ice in carb. throat. I take off and once I'm to 300-500 ft. altitude full carb heat -and at cruise altitude I go for partial until let down. The 520 is a bigger air pump -same design.

I had a PPONK on a C-180 on floats here in Seattle. Many trips up north and never had any more of a problem with Carb Ice than on my0-470. Steve K did do his magic on the carb. when the engine was built. I would certainly discuss with Steve.