Three emulsions better than two?

[Right hand drive]

[Right hand drive]

[GTO Geoff]

RHD,
Managed to find a used version of Larew's book on Ebay.

[Right hand drive]

[Right hand drive]

So reading and thinking more about the 3 v 2 emulsion bleeds it could be about total flow of air into main well and aeration of fuel and when that happens.

If I had a .028” mab and two .028” emulsion bleeds in position #1 and #3. When #1 emulsion begins flowing to main well it is capable of flowing ‘x’ air regulated by mab. As the second e-bleed in position #3 becomes active and flowing air that second bleed would not match the flow of #1 bleed but rather both would be reduced to what the mab would allow, a balancing of flow by changed pressure in the air well. There would be an increase of air ingress into main well and bubbles into the fuel but not proportionate to that of one bleed or more simply not double. Adding a third .028” at #5 position adds even more air but further reduces flow through each e-bleed due to a balancing the further reduced air well pressure. Also less pressure through each bleed = smaller bubbles. This is all cfm through the venturi dependent. My engine must like this amount and condition of aeration at that cfm through the venturi more than the amount two emulsion would give. The same amount of aeration could be achieved with bigger e-bleeds and or mab but this would affect where in cfm flow and therefore rpm range this would happen. My engine may not like that fuel curve.

To expand on this, smaller to larger top to bottom e-bleeds would have a different affect on flow of already flowing e-bleeds as successive e-bleeds become active to larger to smaller top to bottom e-bleeds. This would affect the timing of and amount of bubbles introduced to main well at any particular cfm flow.

Thoughts on the above?

Am I on the right track?

[BradH]

Honestly, I don''t know, which is why I mentioned previously wanting to "try out some things" when everything's back on the road & track.

For example, The air-fuel readings from 3500-7000 on my BG Gold Claw w/ the original .031 / plug / .031 / plug / .031 e-stack were in the right range down low, about the same up high, but had a definite lean "swing" in the mid-range. After mulling over things I've read (learned?) here and elsewhere, I've revised the e-stack in that particular carb to .028 / plug / .020 / plug / .028. I can't tell you if it's a step in the right direction, yet. And I don't think it's totally "out of the ballpark", given I've seen the e-stack on particular set of metering blocks from a respected carb shop and -- without being able to tell you what the emulsion hole sizes were -- it also had an obvious "bigger" / plug / "smaller" / plug / ""bigger" hole pattern.

Another set from the same place had what appeared to be set up with .028 / plug / .020 / plug / .020 (largest on top, smaller on #3 & #5), if I had to guesstimate the sizes. Given the area of two .020s is pretty close to one .028, were they trying to "stretch out" the effect of the middle & lower bleeds w/o introducing too much air in that part of the main well? Dunno... just passing on what I saw.

FWIW, all the rest of my 5-e blocks are set up with #1 and #4 open, and #2, #3 & #5 are plugged. It's basically the traditional Holley 2-emulsion config, only with the lower moved down a bit. The wet-flow tests I had done on some of them showed a decently flat air-fuel ratio across the test pressures used, other than when the MAB was too large and showed a trend towards lean. Nothing about those test results on those particular carbs makes me think the e-stack is "wrong" for them, other than I dropped one of the carb's e-jets from .028 to .026 as one of a couple of changes I made to gain a slightly richer air-fuel mixture across the test range w/o starting to throw more jet in it than I thought should be necessary.

Unfortunately, right now I have lots of "ideas" on things, but am not able to prove anything in live testing until the final reassembly of my POS is finished.

[Right hand drive]

Curious what the x3 with smaller middle does. Might give that a go.

Almost all Demons have the .031/plug/.031/plug/.031 like you Gold Claw and I noticed similar ok - lean dip - ok with an 850 downleg with 28 mab.

That same carb was changed to .028/blank/.028/blank/blank and AFR readings were looking good. Changing out the bottom blank for another .028 did not affect much in the range I was testing. Same with larger bottom or 5th position. This is street strip calibration so I am looking for mid range as much as anything.

The other day I decided to flip to large top to smaller bottom .031/plug/.030/plug/.028 - .028 mab on the same 850. Since my wideband o2 sensor crapped out I had to use the butt meter. As unrefined as that is the performance improvement for the driving I was doing was obvious with improved response and acceleration, breaking traction was easier merging onto the highway. I might not like the o2 readings at certain throttle angles but it must be considered as the new baseline.

Below is the chassis dyno result of a Demon 850 annular I tuned. MJ pri 76 sec 87. Pri power valve 8.5, sec plug. PVCR .059”. IFR .033”, e-bleeds .025/plug/.020/plug/plug. Iab 70, mab .025”



After the butt meter test of the altered downleg I bolted this annular back on for comparison. It was sluggish compared to the downleg. So I made changes along the same lines as the downleg, .028/plug/.025/plug/.020. Again there was a noticeable difference in mid range throttle response and acceleration. Changed from .025 to .028 mab and that woke it up even more. Tried .033 mab and it lost a little down low but gained a little up top. Drilled a set to .030 and I’ll see how that goes. I’ll need to take a look at WOT for both carbies but for now I am liking larger to smaller e-bleed stack for the majority of the driving I do. Curiosity will get the better of me though and I will have to try that smaller middle arrangement.

[HarrysTaxi2]

https://www.youtube.com/watch?v=G-lcmVW-i3k

Here's something that you may find interesting on this subject. I recently bought a pair of his carbs and with only one outing, they have the smoothest fuel curve I've seen yet after trying many different combo's in previous carbs.
I know his carbs are substantially different from a signal standpoint, but some of the fuel flow theories may still apply.

[jmarkaudio]

Smooth or flat fuel curves don't necessarily make the best power. And a couple things I didn't agree with in the video. One he opens the mainwell to a large booster leg, that slows the fuel down and give the air bubbles an opportunity to coalesce. I still feel the best way is to set the emulsion to correct the fuel curve for what a given engine wants, and atomize the fuel at the booster for the droplet size that best suits the combination. With class restricted carbs it isn't always possible, booster style is dictated by rules, then for best performance emulsion can be adjusted to work better in the RPM range the engine is run in.

[HarrysTaxi2]

I don't disagree at all that the flat curve may not be best, but I view that as at least a stable starting point that I was unable to achieve with the many combo's of e-bleed/hsb/boosters I tried before......some were close, but none as less spikey and flat thru the rpm range. I also don't doubt someone smarter than me my have been able to get there with a combo I didn't try.
While the current flat, less spikey curve I observed may not yet be best for most power, they are to date the fastest and quickest carbs I've had on the car (that includes factoring for weather) and yes, I realize it also may have been a cfm increase, but I kinda doubt that was much of a factor given that no previous pairs or these show any vac. reading at full rpm.

I do intend to tweak the jetting and hsb's and to see what those changes may show.

As for how or why he choses the channel sizes, that's above my pay grade and the two of you can discuss that, but I can say his results have been quite positive.