Three hole emulsion

[ArizonaGuy]

I have three or four of these 4150s that have the old-school .028-x-.028 e-stack, with a blank in the middle. Billet blocks BTW. The blanks are counterbored but not drilled through. If I were to drill/tap/use the middle hole, would I just calculate area and divide by three? Or ?

[ArizonaGuy]

Wound up trying .023 x 3, AFRs were really unstable. Just to see how it’d respond I plugged the middle hole, so now .023 x .023, WOW. Unholy throttle response, dead-flat and stable curve. Why didn’t I try this years ago Lol

[HQM383]

Wound up trying .023 x 3, AFRs were really unstable. Just to see how it’d respond I plugged the middle hole, so now .023 x .023, WOW. Unholy throttle response, dead-flat and stable curve. Why didn’t I try this years ago Lol

Great!
All about getting the balance of all orifices right - pressure differential balance.

What carb?

[rgalajda]

"dead-flat and stable curve."
What does this mean ? Show us the readings

[ArizonaGuy]

Wound up trying .023 x 3, AFRs were really unstable. Just to see how it’d respond I plugged the middle hole, so now .023 x .023, WOW. Unholy throttle response, dead-flat and stable curve. Why didn’t I try this years ago Lol

What carb?

750/850 frankencarb. 1-3/8 venturii, annular boosters, 1-3/4 throttle bores. Those annular boosters seem to like less emulsion, at least on my motor. Even before experimenting with that tiny e-stack, it responded well to .025 MABs. So apparently less is more, for this deal at least. As to ‘dead-flat curve’, I suppose that’s relative. It’s certainly flatter and much more stable than it had been with more emulsion.

But I have a 1-1/4 venturii, 1-11/16 bore down leg 650 that likes more emulsion. Same motor. So I guess there is something to be said for ‘it depends’ and/or ‘try it and see’. Although annulars do seem to like less emulsion compared to downlegs, that seems fairly consistent.

[73c34me]

Can you post the engine combo this is for? thanks.

[1972ho]

I’ve tried using a stock metering block on a holley 9380 with the 2 emulsion and could not get that carburetor to get over 11.5 AFR no matter what I tried.But I installed a set of BLP meter blocks on it with 4 emulsion and that was when I got the engine to respond leaner and with jets and no power valves.

[ArizonaGuy]

Can you post the engine combo this is for? thanks.

331 cubic inch SBF, 236* @ .050 solid flat tappet, Vic Jr, open 1/2” spacer, timing locked out at 32*. 3000# car with fuel and my fat ass sitting in it, manual transmission, fairly deep rear gear. Pretty forgiving setup

[FC-Pilot]

I played with. 750 annular booster holley style carb on the dyno quite a bit. My combo was a 358” sbc it’s 10 to 1 compression and hydraulic roller (in the mid 240* @.050) and iron 180 cc EQ heads with a single plane intake. It made right at 480hp. It wanted only one .028 bleed in the top for best power and flat fuel curve. We put almost 50 pulls on that thing trying jets, air bleeds and E bleeds. We tried 3, 2 and then the 1 bleed. All different sizes and combos. I don’t have the notes with me, but we had to keep good notes to keep from getting lost.

Anyway, point is try everything. Ours is in a boat so drivability is different as we doing spend much time on the transition slots. We get on the mains for cruising (which we don’t do much of).

Paul

[HQM383]

Anyway, point is try everything. Ours is in a boat so drivability is different as we doing spend much time on the transition slots. We get on the mains for cruising (which we don’t do much of).

Paul

Good advice with carbs and performance tuning. Experiment outside the box and find what your engine does and doesn’t like for how that engine is to be used.

Paul, with all the dyno fine tuning to find best hp/tq numbers did you do some experimenting of same to see if it were to respond different in practice?

[HQM383]

Wound up trying .023 x 3, AFRs were really unstable. Just to see how it’d respond I plugged the middle hole, so now .023 x .023, WOW. Unholy throttle response, dead-flat and stable curve. Why didn’t I try this years ago Lol

What carb?

750/850 frankencarb. 1-3/8 venturii, annular boosters, 1-3/4 throttle bores. Those annular boosters seem to like less emulsion, at least on my motor. Even before experimenting with that tiny e-stack, it responded well to .025 MABs. So apparently less is more, for this deal at least. As to ‘dead-flat curve’, I suppose that’s relative. It’s certainly flatter and much more stable than it had been with more emulsion.

But I have a 1-1/4 venturii, 1-11/16 bore down leg 650 that likes more emulsion. Same motor. So I guess there is something to be said for ‘it depends’ and/or ‘try it and see’. Although annulars do seem to like less emulsion compared to downlegs, that seems fairly consistent.

Good results so far and seems your having a good time playing and learning carb tuning. Certainly gets you out driving and enjoying the ‘fun’ car more. I bet it’s tempting to block that bottom e-bleed and see how it responds

[rgalajda]

When you guys are saying " flat fuel curve " I take it you are referring to WOT

[FC-Pilot]

I was looking for “wide open” fuel curve. I actually wanted it to move slightly lean in the higher RPM’s. It was dead flat. Now, I then tested stepped down leg boosters and picked up another 30 HP over the best we could muster with the .600 annular boosters that were in it. (Honestly I was crushed as I was kind of stuck on Annulars). We decided to run the downleg boosters as we knew we could gear and prop it to operate in the rpm range we designed the motor for.

We did not go through the carb tuning in the boat as we have so many variables to dial in with the boat setup. If we find a few HP more in carb setup it would not be as noticeable as a gear change, prop change or modification, plate settings or prop location. We still have lots to dial in on the boat. It sure is nice knowing that the engine is known and not a variable.

Paul

[HQM383]

I was looking for “wide open” fuel curve. I actually wanted it to move slightly lean in the higher RPM’s. It was dead flat. Now, I then tested stepped down leg boosters and picked up another 30 HP over the best we could muster with the .600 annular boosters that were in it. (Honestly I was crushed as I was kind of stuck on Annulars). We decided to run the downleg boosters as we knew we could gear and prop it to operate in the rpm range we designed the motor for.

We did not go through the carb tuning in the boat as we have so many variables to dial in with the boat setup. If we find a few HP more in carb setup it would not be as noticeable as a gear change, prop change or modification, plate settings or prop location. We still have lots to dial in on the boat. It sure is nice knowing that the engine is known and not a variable.

Paul

I wonder if a .600” annular booster in a 750cfm configuration over atomizes in some applications? Not uncommon to read of people struggling to dial in that situation.

Are you tied to the typical 750cfm dimensions due to rules or other?

[rgalajda]

"Over atomizes"

Over atomizing the fuel is directly related to induction temperature.
Cooler intake charge requires more finely atomized fuel.

So a heated intake will suffer from " over atomizing the fuel " ( Annular Booster )

An intake manifold with no heat ( crossover ) and air gap style ( cold intake ) will require more atomization from the booster. Such as stepped dog leg booster or an annular booster. otherwise you can have fuel separation ( bad for engine output )

In the 1980's Ford used an annular booster ( .640 ID ) in the 600 cfm holley on there mustangs. These intake manifolds had no crossover heat. Granted this was more to do with low end throttle response ( torque ) and good emissions.

So low gain boosters ( straight booster or dogleg ) for heated intakes and high gain boosters ( stepped dogleg or annular ) for cool manifolds. The stepped dogleg booster doesn't provide much more gain but it does provide better fuel atomization.

David Braswell and David Vizard ran some tests concerning this in the 1970's.

If your switching to a high gain booster ( annular ) the high speed air bleed will likely need to be enlarged.