This may also help, lots of great knowledge and information from "Shrinker" and "Tuner": https://www.tapatalk.com/groups/britishqueen/
Statistics: Posted by bb79ranch — Mon Dec 18, 2023 11:40 pm
]]>
Thanks guys
Statistics: Posted by Christo — Mon Dec 18, 2023 11:19 am
]]>
In simple terms, Emulsion Holes create air bubbles that lower the fuel density, The lower density fuel "floats" above the normal fuel.
That causes the lower density fuel to have a higher fuel surface level than normal density fuel.
Once the fuel surface level is up to the height of the outlet tube it can flow to the booster. At that point the engine starts to run on the fuel.
At low air flow levels thats the physics behind the Emulsion Circuit. You are using air to make the surface of the fuel closer to the discharge outlet.
At higher flows through the carb the main jet restriction causes a reduction of the liquid level in the well and that lower level uncovers some Emulsion Hole Bleeds. When that happens, the air flow through the bleeds blows the fuel along its path. The amount of "blow thru" is controlled by the Main Air Bleed and the sizing of the various Emulsion Bleeds.
Under Acceleration, when the fuel flow into the bowl causes a lowering of the level (high fuel demand). The pressure on the entrance to the main jet is changed, so the flow rate of the jet is changed and that in turn changes the level of fuel in the main well.
You really have to be "on your game" to be successful when messing with Emulsion Jet changes.
Statistics: Posted by rgalajda — Sat Jul 29, 2023 1:39 pm
]]>
]]>
The emulsion bleeds are drilled into the main well. Some early Holley carbs had an emulsion tube in the main well. This can be identified by a solid brass cap , as opposed to to a recessed cap for the main well. This is the inner of the two , viewing from the top of the metering block.
Next to the main well is the Idle Well.
Fuel travels from the bottom of the main well via a port to the idle fuel restrictor ( early Holley carbs ) and enters the idle well . From here it travels up the Idle well where fuel meets with air entering from the Idle Air Bleed.
Next it travels down the Idle Down Channel and exits the curb idle discharge and idle transfer .
Note: the IFR can be at the top of the idle well either under the brass cap ( some early holley’s ) or like newer carbs at the top of the idle down channel.
Main Well
Air enters via a channel connected to the High Speed Air Bleed ( air corrector ) which travels down the channel to the emulsion bleeds , where air can enter the main well fuel.
Maybe this channel is what your referring to as the air well ?
The metering block gasket seals this air channel.
Now if you add fuel to the main well it fills to the float level. The fuel travels thru the emulsion bleeds
to the air channel . So in a static level the fuel in the air channel will be the same as the main well.
When the car is running the top emulsion bleed effects the low rpm range because air will travel to the
first upper emulsion bleed. This is the cruise mode.
As the engines demand for air increases , due to an increase in throttle opening and rpm, the next bleed
( middle) gets exposed , leaning the mixture with air from the air corrector ( HSAB ).
At the top end of the rev range the fuel drops in the channel to expose the bottom emulsion bleed, adding air to the main well to correct the mixture.
At high rpm , just a few thousands change in the HSAB can have a significant effect on fuel ratio.
Statistics: Posted by rgalajda — Fri Mar 24, 2023 1:07 pm
]]>
The MD 750 has downleg boosters, bought new. However, I stripped two bowl screws in it a few years into use and replaced it with another that a builder in Florida had on hand. I believe that was about the time Holley bought out BG, as that builder was getting out of them at the time and told me it was still new. So I'll take it as true it is as new as the original I bought.
Which aspects of a build do you need to know to determine fuel levels in the air well during operation? I'm sure some have greater bearing than others, just not which ones.
My primary assumption, this early in the process, is if you're cruising along at 3500rpm and running solely on the main circuit of the primaries, the fuel level in the well has dropped to at or below the level of the lowest e-bleed. Maybe not, depending on the size of the main bleed, or maybe more specifically depending upon the air flow characteristics through that jet compared to how it flows at each e-bleed, which would determine the amount of downward pressure (atmosphere) felt by the fuel and therefore its likelihood of joining the fuel flow in the main circuit or allowing some of the passing fuel to leak into the air well. That's what I've been looking to see addressed on these forums.
Statistics: Posted by kgb — Thu Mar 23, 2023 9:08 pm
]]>
Changing from .039' HSAB to .025" would have a second effect to fuel ratio at higher rpm WOT. You didn't mention that.
Statistics: Posted by rgalajda — Thu Mar 23, 2023 11:41 am
]]>
You are over analyzing things which leads to little accomplished or mistakes from your assumptions.
I believe you mentioned that you have David Vizard"s Holley Carburetor book . Read page 17 . That is what you need to know.
E-bleeds are the last thing to alter on most carbs when tuning with a AFR/gauge. And usually do not require adjustment.
Statistics: Posted by rgalajda — Thu Mar 23, 2023 11:10 am
]]>
I have A Mopar Performance Engines book (8th edition by Larry Shepard), not sure if it's THE MP book as it doesn't address the TQ very much. Most of what I've learned about them is from the Carter Carburetors/Super Tuning and Modifying book. I was pretty comfortable with it up until I saw what it was doing as it wound out WOT, it's a very nice runner otherwise. At idle, with either carb, my combination doesn't pull much vacuum--well under 10", yet both carburetors idle and run pretty well. I won't know how bad they're actually running until I make some improvements as I find on this forum, then wonder how it was so acceptable for the past couple decades. Doesn't seem the TQ in particular should behave as well as it does when the combination is this far from what they designed it to work on.
Regarding what's going on in the Holley/Demon air wells, without a sensor of some sort to record details of fuel level and vacuum it doesn't look like anyone will be able to declare for certain how and when fuel levels change throughout its range of operation. Not that it's a bad situation, I do like to understand what I can about things like this and am okay when I run into a wall and have to proceed with knowing that it does work without knowing exactly how.
When I read that replacing the .039" MAB with a .025"-ish version would cure the MD's particular ill I just did it and got the result I was after. I knew very little about e-bleed placement and sizing, and believing what I'd read and then experienced about the MABs influencing intitation points for main circuit activity, I assumed from illustrations I'd seen of small holes drilled into the main fuel circuit passages near their high points within the carb body that those were also fed by the MAB. I have not yet found anywhere reading on this forum about that being so, all air going from the MABs to the main circuit must exert its influence solely via the crossover bleeds and e-bleeds within the air wells.
As I record A/F under various conditions, or even just monitor while driving around, I'll be curious to know that change X results in reading Y. Something like changing jets or power valves, or changing an IFR or blade settings/mixture screws should be easy things to estimate and confirm. Numbers, placement and sizing of e-bleeds and the MAB that feeds them is a bit beyond me at this time of ignorant bliss, or heading toward it.
Statistics: Posted by kgb — Wed Mar 22, 2023 11:38 pm
]]>
TQ jetting. If you have, or can get hold of, the Mopar Performance book it has jetting tips on the TQ. One application with a single plane intake, reqd 169 sec jets. So you were going in the right direction. It also recommended the sec blades be 88* at WOT for a single plane & 81* for a dual plane intake. The WOT position of the air valve also changes the A/F ratio. This is the beauty of the TQ. Simple changes at the track.
Something I have done for years on production TQs which noticeably increases performance: solder shut the holes in the sec discharge tubes; then cut off the bullet ends at an angle, similar angle to the Comp Series TQ [ that is where I got the idea from ]. Run a 3/16" drill bit inside the tubes to make sure solder has not blocked them. I use a 80W electric soldering iron & 18g resin cored solder.
Statistics: Posted by GTO Geoff — Wed Mar 22, 2023 5:10 am
]]>
Statistics: Posted by Right hand drive — Wed Mar 22, 2023 2:29 am
]]>
]]>
]]>
]]>
]]>