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- sc2dave
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are Holley emulsion tubes ever "modded"?
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Postby sc2dave »
I thought this might be done,since it helps to mix air and fuel.something like a few more holes in it to further the mixing?
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jmarkaudio
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Re: are Holley emulsion tubes ever "modded"?
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Postby jmarkaudio »
jmarkaudio wrote:The other is the second to last line, "The trick is to get the correct air/fuel ratios at all points..." Adding emulsion should only be about that very thing.
Now using tube emulsion rather than an emulsion well gives you some things to play with, you can add more smaller holes and in different positions without affecting the fuel curve the same as an emulsion well. Emulsion wells work backwards of what you want, they make it richer when the signal is high, until the bottom e-bleed is reached. When the signal drops, like at the shift, an emulsion well has to fill back up, and runs lean momentarily. An emulsion tube carries a much smaller amount of fuel.
Mark Whitener
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panic
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Re: are Holley emulsion tubes ever "modded"?
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Postby panic »
Very interesting.
With a fixed well shape (tall narrow cylinder), the volume is affected by the "bulk" of the tube (regardless of the tube's interior).
Assuming the tube's internal volume is constant, how much effect does making the tube wall much heavier have?
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jmarkaudio
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Re: are Holley emulsion tubes ever "modded"?
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Postby jmarkaudio »
Well size, or volume, always has an effect, as well as surface friction from both the tube and added surface area of the well. As a result the well has to be sized accordingly to keep the signal required to lift the fuel close. Tube emulsion is beneficial in that the air is dispersed more evenly into the well and the "Bubbles" will not tend to coalesce as much. It makes the fuel leaving the mainwell and exiting the booster more consistent. But you already knew that, didn't you...
Mark Whitener
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panic
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Re: are Holley emulsion tubes ever "modded"?
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Postby panic »
Thanks.
Looking at factory carburetors, early vs. late, same engine.
All wells are .342" ID, same height.
Early tube is (almost) a 1/2 cylinder, flat on one side, 1" long (well empty volume .092" in3)
Late tube is only .218" OD cylinder, 1" long, nozzle is (well empty volume .146" in3)
Tube interior volume same for both .1405" ID
Any thought as to what effect this has?
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- Troy Patterson
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Re: are Holley emulsion tubes ever "modded"?
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Postby Troy Patterson »
are Holley emulsion tubes ever modded?
If I told you, I'd have to kill ya
Troy Patterson TMPCarbs.net TMP Carbs
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- T-flow
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Re: are Holley emulsion tubes ever "modded"?
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Postby T-flow »
Kill him and tell me all about it ............
T-flow
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- swatson454
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Re: are Holley emulsion tubes ever "modded"?
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Postby swatson454 »
T-flow wrote:Kill him and tell me all about it ............
T-flow
That's awesome LOL
Live in such a way that those who know you but don't know God will come to know God because they know you.
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jmarkaudio
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Re: are Holley emulsion tubes ever "modded"?
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Postby jmarkaudio »
panic wrote:Thanks.
Looking at factory carburetors, early vs. late, same engine.
All wells are .342" ID, same height.
Early tube is (almost) a 1/2 cylinder, flat on one side, 1" long (well empty volume .092" in3)
Late tube is only .218" OD cylinder, 1" long, nozzle is (well empty volume .146" in3)
Tube interior volume same for both .1405" IDAny thought as to what effect this has?
Curious more to know what carb. Try drinking out of a coffee stirrer vs a garden hose (extreme), the larger the well, the harder it is to lift the fuel, but will depend on the emulsion used to help lift the fuel. The half moon tube is different, how does the amount of emulsion compare between early and late, position of the e-holes, and how the flat side is positioned in respect to the exit toward the booster? .342 is big, and the tube interior size is as large as the mainwell on some small Holley 4 barrels, it's a lot of fuel to lift unless it's a very large engine.
Mark Whitener
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panic
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Re: are Holley emulsion tubes ever "modded"?
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Postby panic »
It's that infamous coal-burning instrument, the Linkert Model "M" (side-draft plain venturi).
What I can't figure out is that the air-correction opening is reamed/drilled (not cast), and not to a fractional or metric size, but there are at least 5 different sizes used during the period 1933-65 - and all vastly larger than the total of all air-bleed holes in the nozzle (and there's a low-speed circuit air bleed as well).
Aren't Holley air-horn mounted air-bleed jets about the same size as the emulsion holes?
Is any smaller correction area (than the nozzle total) a tuning point as a restriction, or do emulsion tubes receive leaked air from the interior?
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jmarkaudio
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Re: are Holley emulsion tubes ever "modded"?
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Postby jmarkaudio »
With a Holley the MAB is usually between .025 and .040, emulsion bleeds are around .028+- and will have 1-5 bleeds in an emulsion well. There was a PHR article that used .093 MAB's to try to improve mileage, not something I would recommend for the average person to play with. How much emulsion is used to set the fuel curve depends on the carb size and how much the engine pulls through it. I can't help much with your Harley carb a I have not seen one, but one other thing I saw that may have an effect is the air filter type used, on a quick search I saw mention of an oil bath filter. The calibration would be different than a dry element filter.
Mark Whitener
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panic
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Re: are Holley emulsion tubes ever "modded"?
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Postby panic »
Thanks, but still mysterious.
This Linkert is a 74" twin with a single 1.56" throttle and 1.31" venturi.
The combined area of 5 × .028" AB is about the same as a single .0626" MAB; what effect does more than doubling the area (.093") have?
Doesn't it stop being the restriction when it exceeds the combined area?
My first impression:
If the MAB area is smaller than the combined total, it will restrict air (and enrich) mixture at any point before the exposed ABs reach its area (#1 through #?). At low RPM, only the top AB hole is uncovered (above the well fuel level), etc.
E.g., with 5 × .028" AB (total .0031 in2) and a .040" MAB (.00126" in2), it will not be the bottle-neck until enough holes are uncovered to match its area.
1 hole exposed = .00062 (MAB = 205% area, no effect)
2 holes .00123 (MAB = 102%, no effect)
Now, the AB total and MAB are nearly a match. Only after this point is the MAB area less than the AB total:
3 holes .00185 in2 (MAB = 68%, richer)
4 holes .00246 in2 (MAB = 51%, richer)
5 holes .00308 in2 (MAB = 41%, richer)
The smallest MAB to have no effect at any speed should be slightly greater than the AB total, or .0626".
What factors am I leaving out?
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jmarkaudio
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Re: are Holley emulsion tubes ever "modded"?
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Postby jmarkaudio »
Not sure why they went to a .093 MAB, but I would hate to see the AFR on that one at WOT... Remember that air is compressible, fuel is not. So even though the MAB is smaller it will not be a linear effect, even going to .040, .030, and .025 will change the way it acts. It would be interesting to see the signal required to reach each level of bleed with different emulsion and MAB's, however there are a lot of variables in the mix. Venturi size and shape, booster type and positioning in the venturi, main and emulsion well sizing, etc. On a Holley, even the transition and idle circuit metering will effect the main metering as they feed off the main well above the main jets, they can become a bleed back into the mains at higher RPM. If the Linkert idle and transition circuits are divorced from the mains it will impact the emulsion needed. Can you put an O2 on it, like an LM1, and log the changes it makes with the different arrangements? You can still get a single channel LM1, with the RPM converter you can log and download to see the effect.
Mark Whitener
www.racingfuelsystems.com
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Good work isn't cheap and cheap work can't be good.
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- RCJ
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Re: are Holley emulsion tubes ever "modded"?
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Postby RCJ »
E.g., with 5 × .028" AB (total .0031 in2) and a .040" MAB (.00126" in2), it will not be the bottle-neck until enough holes are uncovered to match its area.
What math formulas did you use to find the combined area of the AB and the MAB
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- maxc
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Re: are Holley emulsion tubes ever "modded"?
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Postby maxc »
Carbs should be made with moveable metering rods for AB's and or emulsion tubes
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