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"Calling All "WALBRO" Experts"

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Old 11-06-2005, 03:01 PM
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tande
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Default "Calling All "WALBRO" Experts"

I've noticed that some "Walbro" carbs. use a check valve in the high speed fuel circuit spray/bar (just before the fuel is released into the air/stream---& of course some don't)---My guess is this is to prevent air back/bleed into the fuel reservoir when not operating on the high speed circuit---Can anyone discuss this & the criteria used to decide when this style carb. is beneficial & when not?---
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Old 11-06-2005, 03:32 PM
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Antique
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Default RE: "Calling All "WALBRO" Experts"

The REAL expert on Walbro carbs is in Cass City, Michigan, at the Walbro factory...His name is Luis Salas...He KNOWS Walbro carbs....
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Old 11-06-2005, 06:15 PM
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Default RE: "Calling All "WALBRO" Experts"

Not being an EXPERT - I have to ask which model carb you are concerned with .
I run into some odd stuff on these carbs from time to time and find that some "Walbro " types (Tillotson/Bing) use a different approach to some of the features. Some good ---- some not so good for model airplane engines.
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Old 11-06-2005, 10:05 PM
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Default RE: "Calling All "WALBRO" Experts"

I am no expert also.......but i do have a Walbro carb book. I will see what it says about the check valve. Regards......Capt,n
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Old 11-07-2005, 02:20 PM
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tande
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Default RE: "Calling All "WALBRO" Experts"

Thanks Guys for the response!---For those who care, I just talked with Luis Salas at "Walbro" (Thanks to RCIGN1 for that tip!) & he confirmed that the check/valve is indeed designed to prevent air back/bleed into the fuel reservoir where it CAN mess with idle circuit fuel calibration---Said his personal opinion is that ALL carb models should have it & knows of many in the racing world who modify their carbs to use it (Sounds like the spray/bar-check/valve is available as a service part---forgot to ask---oh well!)---Now why does all this concern me?---Well, I have two YW48 twins (Nice engines aside from this particular complaint) that I cannot get to idle down in the air, to set/up for a landing (Idle sounds like maybe 3000 RPM, who knows)---After they are on the runway & come to a stop the RPM's will drop right down---Seems as though it has something to do with the engine being "Windmilled" by the prop while moving through the air & I am wondering about the low speed mixture "Leaning out" with the throttle pulled back---I can somewhat help the condition by adjusting the low speed mixture to the rich side but then the midrange & transition falls all apart!---Thought about the spark advance curve not cooperating---Talked with "Terry" at "C.H. Electronics" & agreed it might be a possibility---Tried one of their (C.H.) spark advance circuit boards---No dice!---Any thoughts Guys!--
Thanks to all---
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