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 Post Posted: Wed Mar 16, 2011 9:28 pm 
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I've notice on a 4150 style main body (not Holley) that the air bleeds have been move to the top surface of the body similar to an HP Dominator, no longer in the entrance of the venturi. I know this will change the metering requirements, however, I would think this may be detrimental if the scoop is not the best and air flows more across the bleeds at higher speeds than straight down. Comments? I remember the discussion of bleeds on a plinth, like a pedestal, to put it up in clean air, yet most of the new stuff all seems to put them flush.


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 Post Posted: Wed Mar 16, 2011 9:54 pm 
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Donee and I have talked several times about having the air bleeds plumbed with hoses to a "neutral" location as far as air is concerned, especially the MABs. Something to keep turbulence from them down track. I just haven't had time to do anything with that to this point. May look into it some time later this season.

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 Post Posted: Thu Mar 17, 2011 4:57 am 
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So you would have a flexible extension on them to place them some where else inside the scoop. I would think that outside the scoop would not be a good place
with all the heat from the engine. :-k

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 Post Posted: Thu Mar 17, 2011 9:02 am 
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All tubes, including bowl vents into a common header with one opening. That way they would all see the same air pressure. Where to place the "common header" is still up for grabs as is the tubing size and length in order for it not to be a restriction. This is the kind of stuff that Donee and I talk about in those weekly phone conversations we have.

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 Post Posted: Thu Mar 17, 2011 9:45 am 
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I have thought about the common position as well, looking at the Weber Power plates that is how they did it. I would think the position of highest pressure, but still stable air would be the best.


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 Post Posted: Thu Apr 07, 2011 12:30 pm 
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The people who dont put the air bleeds on a plinth inside the air horn possibly havent fully understood some of the physics of an emulsion carburetor.
The bowl vent can be moved etc to cause very subtle changes in AFR reaction to scoops etc but the HSAB must be located in stable atmospheric pressure (on a plinth) so that the effect of operation of the HSAB is correct and predictable in all weathers. Correctly done, the tune of an engine varies very very little with differences in air density at race tracks etc. If the engine draws enough air per barrel or the carby settings are bad enough that the HSAB is outside its function range then it doesnt matter where you put it because its doing nothing. But thats not good technique.
Correct carburetor AFR control can be obtained without HSAB but not in a mass production hotrod industry sense.


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 Post Posted: Thu Apr 07, 2011 1:05 pm 
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Good to see you back, hope all has been well. And thanks.


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