| | Joined: Jan 2004 Posts: 18,962 Likes: 3 Member/15,000 posts | | Member/15,000 posts Joined: Jan 2004 Posts: 18,962 Likes: 3 | Reg, Bill and I both have plenty of 152 time for comparison, and Bill and I both lean our 150's fairly aggresively! You didn't mention leaning. I believe a rich mixture may be more prone to icing due to evaporative cooling of the throttle plate in the carb (same basic carb as the O-235, BTW). Do you lean, and when? (Consider this research!)
Oops, Sorry! Re-read your post and you do lean! I still don't understand why some O-200's seem to have icing problems, but apparently you aren't alone!
Last edited by Carl_Chitwood; 08/23/06 04:28 PM.
| | | | | Joined: Jan 2004 Posts: 13,969 Member/10,000+ posts! | | Member/10,000+ posts! Joined: Jan 2004 Posts: 13,969 | I have the opposite experience with carb ice than Bill. And I too, live in the PNW. Almost every flight gives me some carb ice. Sometimes it is to the point of leaving the heat on and leaning for the entire flight. At other times, it is a short duration one time shot sometime during the flight.
Curious? What throttle settings do you usually use, Reg? Like I said previously, 72G usually was flown with the throttle just back off a tad from full throttle.......... | | | | | Joined: Dec 2003 Posts: 2,873 Likes: 3 Member/2500+posts | | Member/2500+posts Joined: Dec 2003 Posts: 2,873 Likes: 3 | Another potential advantage to the Lyc is the availability of a SparrowHawk conversion, a nice compromise that increases performance without adding weight like the 0-320 conversion does. | | | | | Joined: Mar 2006 Posts: 4,768 Likes: 3 Member/2500+posts | | Member/2500+posts Joined: Mar 2006 Posts: 4,768 Likes: 3 | Bill:
I usually run 2450-2500. Anything more and speed gets up to the top of the green arc, which is fine on a smooth day, but I stay away from the yellow if there are bumps.
Also, I am thoroughly a scotsman, and I love that +/- 5 gph.
Reg | | | | | Joined: Mar 2006 Posts: 4,768 Likes: 3 Member/2500+posts | | Member/2500+posts Joined: Mar 2006 Posts: 4,768 Likes: 3 | As I sit here and cogitate ... there is another possible contributing factor ... my baffling needs a little work. Since the engine never runs hot, this is an item that is waiting for the next annual. But the effect may be that temps in the engine compartment may run a little low. Even on the hottest days and long slow climbs oil temp stays well inside the green.
Reg | | | | | Joined: Dec 2003 Posts: 2,134 Member/1500+posts | | Member/1500+posts Joined: Dec 2003 Posts: 2,134 | As I sit here and cogitate ... there is another possible contributing factor ... my baffling needs a little work. Since the engine never runs hot, this is an item that is waiting for the next annual. But the effect may be that temps in the engine compartment may run a little low. Even on the hottest days and long slow climbs oil temp stays well inside the green.
Reg I may be wrong but I believe the baffling is there to ensure the engine runs cool. You're implying that your baffling is in poor shape and causing your engine to run too cool contributing to your carb ice exposure. I don't think that's true. The cooler your engine runs the better for overall longevity; heat kills engines. I'd invest in a carb temp guage and use heat when indicated.
Tim
'76 C-150M, San Antonio
| | | | | Joined: Mar 2006 Posts: 4,768 Likes: 3 Member/2500+posts | | Member/2500+posts Joined: Mar 2006 Posts: 4,768 Likes: 3 | Tim:
It depends on WHICH baffling is in need of attention. The baffling around the top of the engine is in OK condition, else it wouild be addressed right now. But there is a 1/4" gap all the way around the air filter, which lets cooler air into the bottom of the cowl.
Interestingly, I have seen this condition on several 150's.
Reg | | | | | Joined: Jan 2004 Posts: 13,969 Member/10,000+ posts! | | Member/10,000+ posts! Joined: Jan 2004 Posts: 13,969 | But there is a 1/4" gap all the way around the air filter, which lets cooler air into the bottom of the cowl.
Isn't this the same for all 150's? I don't recall ever seeing baffling around the air filter? hmmmmmmmmmmmmmmmmmm  | | | | | Joined: Jan 2004 Posts: 18,962 Likes: 3 Member/15,000 posts | | Member/15,000 posts Joined: Jan 2004 Posts: 18,962 Likes: 3 | But there is a 1/4" gap all the way around the air filter, which lets cooler air into the bottom of the cowl.
Isn't this the same for all 150's? I don't recall ever seeing baffling around the air filter? hmmmmmmmmmmmmmmmmmm According to the late 150 parts manual, cowling seals were installed around the air filter for the later model cowling (fiberglass nose piece, I believe 1972 models and up). These may have been removed if a Brackett foam air filter has been installed, but I'm not certain. Apparently none of the pre-72 models had these seals. I'm pretty certain it won't make enough difference to affect carb ice, Reg!  | | | | | Joined: Mar 2006 Posts: 4,768 Likes: 3 Member/2500+posts | | Member/2500+posts Joined: Mar 2006 Posts: 4,768 Likes: 3 | Carl:
Interesting. The AP we have been talking to, and the gentleman who did the pre-buy, and was an old time Cessna hand, both pointed out the lack of a seal around the air filter, which is of the bracket variety.
Perhaps more research is in order before I get excited about sealing this up.
And it was such a nice explanation for the fact that Juliet seems to be such an ice maker. More so than the 150, of a later model, that I flew early in my learning, and conducted my first solo.
Another explanation I have heard is that the mixture may be set too rich. But then, why the fuel burn, which runs a very low 4.5 to 5.25 gph?
I don't consider it a big problem. One just needs to stay tuned to what the engine is doing.
Reg | | |
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